You keep adding things to your request tho
No remote control/monitor software is truly hidden, at least not from the ones who know. There are some programs that fall in the category of spying software but they are meant for one to one tracking/remote control and not to monitor multiple PCs concurrently in an organization.
Also, if any employees close the program, the management can see that, and have a "talk" or even reprimand the people who terminated the remote software. It's simpler to set a rule like "you are not allowed to terminate programs on your PC" than try to be stealthy about it. After all, if your goal is to have the people at work, focus at work, you will achieve it better if they too know that they are actively monitored.
And to be honest, employees should run as simple users with limited rights while software such as remote management, a/v, etc to run with admin rights. That way a user cant disable or remove any type of software from the companies PC.