Trump can't voluntarily stop being President because if he does, the barriers he has put up between his personal financial records, including his tax returns, and prosecutors will disappear. All of the arguments before various Courts trying to prevent those records from being released are based on the fact that Trump is President and fending off those legal challenges would distract him from watching Fox News and tweeting about it all day addressing the pressing concerns of the nation.
I don't know what is in these records. But it's gotta be bad given how strenuously he is fighting to keep them secret. Not running for reelection would be tantamount to just handing them over to the investigators and prosecutors who he has been fighting throughout his presidency.
