You may use 'SEPUninstaller' in SEP CD2 to uninstall SEP clients remotely, as there is no option to uninstall SEP in the SEPM.
To run a scan on any computer or a group, you can right click on it and select 'Run command on Clients/Group' and may select 'Scan' or 'Update contact and scan'.
Or you may schedule a scan in Antivirus and Antispyware Protection Policy under 'Adminstrator Defined scans'.