Yes. You can delete sandboxes. However, youcan delete only those that aren't published.
See Also
Help And Training CommunityBefore you delete a sandbox, you must first confirmthat the sandbox isn't active.
Caution: Deletion of partial content of a sandbox is risky.It's recommended that you don't use this option.
After you've tested your application changes, you must move those changes to theintegration sandbox. Publish your integration sandbox and then delete all the test-onlysandboxes. You can then create and work in new sandboxes, including a new integrationsandbox.
