Please check if the following tutorial solve your needs:
Update! Actually, BEFORE you follow the instruction and remove the replica from the availability group, first try to find out the root cause so that you can take steps to mitigate it from happening again! This is important.
Note: for the second step in the tutorial after you remove it from the AG and need to fix it, check this post:
https://www.sqlskills.com/blogs/paul/creating-detaching-re-attaching-and-fixing-a-suspect-database/