Unable to DELETE config/user_token

**Describe the bug**

When trying to delete `config/user_token`, it fails with:
```
❯ vault delete artifactory/config/user_token                   
Error deleting artifactory/config/user_token: Error making API request.

URL: DELETE  /v1/artifactory/config/user_token
Code: 405. Errors:

* 1 error occurred:
	* unsupported operation
```

**To Reproduce**
 see above
