I want to bulk delete or resolve issues in my Sentry project.

Note: Deleting all of your issues may not be the best choice. Read about other options here.

With bulk actions (both deleting and resolving) you can only do up to 1000 issues at a time. When in your issue dashboard, you can select issues matching a given query, is:unresolved for example, and then select Resolve or use the dropdown to Delete Issues:

Should you wish to use the API you can use the Bulk Mutate endpoint or Bulk Remove endpoint for resolving and deleting, respectively.