"Monitor > Agent Monitoring > Alerts > Event Logs" for Event log based monitoring, Select the agent that has the offending monitor set and use the cross next to the monitor set to remove it from the agent.

"Monitor > Agent Monitoring > Assign Monitoring" for performance, service and process monitoring

"Monitor > SNMP Monitoring > Assign SNMP" for SNMP based monitoring

Select the agent and then the monitor set (you can use the little notepad and pencil icon next to the assign monitor set to quick load it) then use the "Clear" button to re move the monitor set/s.

Might be good to review the training vids, you can sign up from this link;

portal.kaseya.net/.../Logon.aspx