Deleting all your issues to just get rid of them may be tempting, but in many cases it's a temporary fix, and there are better solutions. If none of these situations apply, it might be appropriate to delete the events.
I have a lot of similar issues that aren't being grouped together
After setting this up, you may want to merge the previous issues together to clean up the UI.
I don't want to see these issues
You can filter out a number of commonly unwanted issues from the UI by navigating to your Project > Settings > Inbound Filters.
These issues aren't a problem anymore
You may want to resolve the issues instead, which can be helpful if you want to search for them later on.
I've used up too much of my quota
Deleting an event won't affect your quota, as it's already been processed by Sentry.