You wouldn't use a debugging tool to modify the properties of a program. Ollydbg doesn't really have the exe modifying capabilities to do that -- it's really just for debugging and making patches to ASM.
You flat out can't make a program not appear in the task manager. The task manager is literally a list of all the currently running programs and services acknowledged by the OS -- you'd have to literally modify the Windows installation on the computer to make an exception for your program and not display it. Good luck with that one.
As for not appearing in task bars, that can probably be done with some kind of EXE modifier program like resource hacker, PE explorer, or LordPE.