Did you create that table in custom scope application or some existing system application such as HR Scope?
Please share some images
a) If you have created this custom table in Installed Scoped System Application then you cannot delete it from UI. Refer below link on how to do it.
Delete Custom table created in installed Scoped System Application
b) If you have created this custom table in custom scope application then you should be able to delete that as an admin
Regards
Ankur
