Delete permissions are dependent on the Modify permissions. For example, if the user does not have permission to Modify a record, they also cannot Delete a record. If you wish to set a time limit for modifications, you will need to setup a Formula Checkbox with a formula along these lines:
Now()<= [Date Created] + Hours(1)
This would provide a Checked value for 1 hour after the record is created. You can then use this Formula Checkbox in the Custom Rules under the Modify permissions and only allow Modification if [Formula Checkbox] is Checked.