THis maybe a stupid question but i absolutly cant find a way how to restore all to default in crysis menu, if i delete the cvar and set in ingame menu everything on very high and restart,i still got some setting set to own and not very high, can tell me please how delete it?

In your Crysis 3 folder, CVar created new system.cfg and made changes to it but it also created backup file. You schould see system.cfg and system.cfg.bak in your game main folder. Delete first one and rename last. Also delete autoexec.cfg.