You can remove the policy assignments by selecting a policy and then removing the device from the Assignments section on the Policy Summary page. You can also do this by clicking the appropriate device on the Devices page and disassociating a policy by using the Effective Policies section.
After a policy is disassociated from a device, it is unenforced on the device. For more details on unenforcement of a policy, see Section 17.13, Unenforcing Policies.
You do not need to delete a policy to disassociate it from a device.