A QoS policy cannot be deleted until its associations with all the ports are removed.
Since one shaper policy can be assigned to multiple ports, you must remove all the associations to the ports before deleting the shaper policy.
Use the following CLI syntax to remove a shaper policy from a port and then delete the shaper policy from the QoS configuration:
config>port>ethernet>access>egress# no shaper-policy
config>qos# no shaper-policy policy-name
config>port>ethernet>access>egress# no shaper-policy
config>qos# no shaper-policy shaper_policy_2