They aren't hard to find if you just look
Of note here:
"Replacing a presumptive nominee before the national convention
The Democratic and Republican parties do not formally nominate candidates until delegates vote at the party's national convention. The Democratic National Convention will take place from August 19-22, 2024, and the Republican National Convention took place from July 15-18, 2024.
A party's presumptive nominee, meaning the candidate who receives an estimated majority of delegates after state nominating events, could be replaced at the convention. Delegates could elect a candidate who they were not initially bound to at the time of their state's election. Both state law and party rules govern how a delegate must vote at the national convention, including whether a delegate remains bound to a withdrawn candidate and for how many rounds a delegate remains bound to a candidate."