Write a trigger with its test class for only system admin user should be able to delete the task.

....Trigger....

trigger DeleteCheck on Task (before delete) {
    Id profileid=Userinfo.getProfileId();  
    profile profilname=[select Name from Profile where id=:profileid];
    
    for(Task accountDuplicate:Trigger.old)
    {
        if(profilname.Name!='System Administrator') {
            accountDuplicate.addError('No Access for Deletion');                                    
        }
        
    }
}

....Test Class....

@istest

public class DeleteCheckTest  {

    @istest

    static  void TestAccountTrigger(){

        Task Tcc = new Task();

        Tcc.Subject =  'Email';

        Tcc.Priority =  'Low';

        Tcc.Status = 'in progress';

        insert Tcc;

        

        Id profileid=Userinfo.getProfileId();

        profile profilname=[select Name from Profile where id=:profileid];

        if(profilname.Name!='System Administrator')

        {

            Tcc.addError('No Access for Deletion');

        }

        else{

            delete Tcc;

        }

    }

}