I do know how to reset my RB2011 (with the reset button, or winbox, or the config site).
But even after a reset, files (like backups) remain in the “File” menu of the router.
If files remain there, what else will stay foot in the RouterOS that we cant see?
Is there a way to really, totally reset the routeros?
Netinstall with disk format. Only licence stays on the disk.
Thx, will google on that!
Searching the forum is enough: http://forum.mikrotik.com/t/nand-format-and-netinstall-on-rb532/12139/1
And reading manual: http://wiki.mikrotik.com/wiki/Netinstall
Thank you. A few more beginners questions will popup the days following… 
Search the forum before ask. There is no begginers question that was not answered already . Starting with mikrotik ros means a lot of reading and a lot of tryouts. Really painfull trip will be rewarded by new knowledge gain.