Hi Silvia - Welcome to the Atlassian Community!
You should be very careful about allowing the deletion of anything in Jira. It's usually best to include some type of status in your workflow such as Discard or Abort (Done type statuses). And just leave the issues there.
But if you really need to delete them, you need to change the Permission Scheme for the Delete Issues setting. Definitely don't allow persons other than Administrators to have that permission.
Also check the Schedule Issues permission to allow Date changes and Releases.
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