Hello,
What version of SEP are you running?
In your case, since you would like to have NTP uninstall only on certain number of clients, make sure you have all these clients moved to a new group and then perform the steps provided in the article below.
Check these Articles:
Symantec Endpoint Protection: How to remove Network Threat Protection and Email Tools through the Symantec Endpoint Protection Manager.
http://service1.symantec.com/SUPPORT/ent-security.nsf/2326c6a13572aeb788257363002b62aa/9c45834bf04156c7882573ad00564f30?OpenDocument
How to add or remove features to existing Symantec Endpoint Protection (SEP) client installations
http://www.symantec.com/docs/TECH90936
Note: To uninstall NTP completely, a Restart of Machine is important after performing the steps provided in the article above.
Hope that helps!!