NO way to uninstall SEP clients from SEPM but you can do it remotely by using client_remote tool (PushDeploymentWizard) of SEP then deploy the competitive uninstall script (Seprep.ini). Configure the seprep.ini like it shows below.
[Settings]
ShowGUI=N
ShowMessageBox=N
MessageBoxText=Prepairing your system for Symantec Endpoint Protection 11.0. During this process other antivirus products will be removed.\n\nIf you are prompted please fully remove these products.
AutoRunAfterUILoads=N
AskBeforeRemoval=Y
SilentMSIInstaller=Y
RemoveSymantec=Y
CheckDiskSpace=Y
ResumeAfterReboot=Y
Regards,
JM