The controversial former Plaid Cymru politician Neil McEvoy has withdrawn his application to re-join the party he was expelled from.
In a letter, South Wales Central AM Mr McEvoy alleged a lack of "natural justice" and "due process".
He was due to face a disciplinary panel discussing the case on Wednesday.
Plaid AM Helen Mary Jones said the process had been fair, open and honest. "Mr McEvoy is not relevant to Plaid Cymru anymore," she said.
"Quite frankly, we spent enough of our time and our resources dealing with this issue, and now we need to get on and do what this party needs which is speak for Wales at this really troubled time."
The party had expelled Mr McEvoy, who is also a Cardiff councillor, in March 2018 over allegations of disruptive behaviour at a party conference.
He had already been thrown out of the party's group in the Welsh Assembly. Mr McEvoy has not ruled out applying for party membership again at a later date.
Mr McEvoy had expected the panel to refuse his application.
"Grassroots members know that during my expulsion my behaviour has led to an increase in membership, increase in interest in sovereignty and Plaid actually winning elections in Cardiff," claimed Mr McEvoy on Wednesday.
"It is also clear that I have significant support from members across Wales who want to see me back in the party. I'm not prepared to turn my back on these members," he said.
The end of the story?
By Daniel Davies, BBC Wales political correspondent
Plaid Cymru AMs hope to draw a line under this, but there might yet be another chapter.
Mr McEvoy has not ruled out applying to join Plaid again, particularly if people sympathetic to him are elected to the party's executive in the autumn.
But even if all routes back into Plaid are closed, the party could yet find they have to contend with Mr McEvoy.
He says he will stand as an independent candidate in the Cardiff West constituency where he and Plaid would dearly love to dislodge the sitting AM, Mark Drakeford.
'Tried to rig'
In June, a disciplinary panel asked to decide whether Mr McEvoy should be re-admitted to Plaid recommended the panel be disbanded after its work leaked to the media.
The panel was to meet afresh with new members on Wednesday evening in Aberystwyth. A barrister, Emyr Jones, was to chair the meeting, which has now been cancelled.
In the letter sent by Mr McEvoy to solicitors working on behalf of Plaid Cymru, the independent AM said he was withdrawing his application due to "an absence of natural justice" and an "absence of due process".
Mr McEvoy's letter alleges that two members of the disciplinary panel had "expressed prejudiced views about" him and were not impartial.
He alleged he was not told until Friday before the meeting that he could have legal representation at the meeting, and that at a previous meeting the chair had taken a "highly unusual" move to use her vote to "tie matters".
He also claimed that leaks about the work of the panel were "malicious" and orchestrated to give the chair of the panel an excuse to scrap "a non-compliant panel", and that it should have sought his opinion before it did so. He said he did not know how the panel members were selected and on what basis.
"Ultimately I did not want to let down so many people today by appearing before a panel which some people have tried to rig", he wrote.
Helen Mary Jones, Mid and West Wales Plaid Cymru AM, said Mr McEvoy can expect a response from the party's solicitors.
"From my own personal perspective I feel that the process has been dealt with fairly, openly and honestly," she said.
Ms Jones said it was possible that Mr McEvoy could apply again, but she said that would be "rather extraordinary".
She said those who have respected the process and not spoken publicly "about their views about Mr McEvoy will have the opportunity to do so".
"I think if people do make that choice, some of those currently supporting Mr McEvoy or feeling he will be an asset to the party may change their minds."
Mr McEvoy was expelled from Plaid Cymru for 18 months in March 2018. This was later reduced to 12 months, allowing him to reapply in the spring of this year.
His re-application faced considerable opposition from elected members in the National Assembly.
Neil McEvoy was expelled from the National Assembly Plaid Cymru group in January 2018 after a "breakdown of trust", caused in part by a demand by the AM to see correspondence about him from his colleagues.
He had been suspended twice before then, the first of which was triggered by a tribunal that found that a remark Mr McEvoy made to a Cardiff council officer amounted to "bullying behaviour" - leading to him being suspended for a month.
He had been facing a party investigation into his behaviour at the same time, which culminated in his expulsion after it found him guilty of misconduct during the 2017 Plaid Cymru spring conference.
According to complaints made against Mr McEvoy, Plaid chairman Alun Ffred Jones said he had asked the AM not to hold a rally at the conference, a request that was ignored when a welcoming party greeted Mr McEvoy at the Newport venue.
He was asked by Mr Jones not to make any reference to the tribunal in his speech to conference, but Mr Jones said Mr McEvoy made frequent references to it.
Mr McEvoy had pitched his bid to rejoin the party as an opportunity to unseat First Minister Mark Drakeford.
In the 2016 assembly election Mr McEvoy came within 1,176 votes of beating the Cardiff West Labour AM.
He is a Cardiff councillor for the ward of Fairwater, and had helped campaign for Plaid Cymru in a recent by-election in Ely where the party was successful.