/**
* @author       Manoj Dega
* @date         21 July 2018
* @description  Restrict to non-admin users to delete the tasks
*/
trigger DeleteTaskAdmin on Task (before delete) {
    Id profileId = UserInfo.getProfileId();
    Id sysProfileId = [SELECT Id FROM Profile WHERE Name = 'System Administrator'].Id;
    
    if(trigger.isBefore && trigger.IsDelete) {
        if(profileId != sysProfileId) {
            for(Task tsk : trigger.old) {
                tsk.addError('You do not have rights to delete this record. Please contact with you System Administrator');
            }
        }
    }
}