Use sp_drop_qpgroup to drop an abstract plan group.
The following restrictions apply to sp_drop_qpgroup:
Only a system administrator or database owner can drop abstract plan groups.
You cannot drop a group that contains plans. To remove all plans from a group, use sp_drop_all_qplans, specifying the group name.
You cannot drop the default abstract plan groups ap_stdin and ap_stdout.
This command drops the dev_plans plan group:
sp_drop_qpgroup dev_plans