There is a limit in place to prevent people from rage quitting.
A rage quit is when someone is so upset over something that happened to them on the site that they decide to stop playing and take their ball home with them, and attempt to delete everything they ever posted.
The problem with that is that when you post an answer, you license it to the site under the CC BY-SA 4.0 license (See also: "Stack Exchange and Stack Overflow have moved to CC BY-SA 4").
You cannot rescind that license by deleting everything.
You can always delete an answer you feel is not up to standard, but you rarely need to delete more than 5 in a day. If you run into that limit, perhaps you need to rethink how you answer and not post the answers you are now unhappy with in the first place.