I passed by this experience after the deletion of a DHCP superscope where the Superscope reverts back after the DHCP server is rebooted or after the restart of the DHCP service. To properly remove a DHCP Superscope, you can perform any of the following methods:

1.      Right click on the Superscope and click delete. It’s safe and won’t have any impact on the Sub-scopes under this DHCP superscope. In fact you will receive a message that confirms the deletion without impacting or deleting any child scopes as per attached below.
DHCP Superscope deletion


2.      One other way is to deactivate the sub-scopes (under your DHCP Superscope), move these scopes and then activate them. After all sub-scopes are moved, the DHCP superscope was removed/deleted automatically.
DHCP Technical Documentation: