If in Privacy Mode ("Ctrl+Shift+H") will show "Private browsing" on the title bar if you have a menu bar, the Clear Recent History on the Tools menu is grayed out (had to reposition monitor to see that) and does nothing. If you don't show the menu bar then in Privacy mode the "Firefox" changes from orange to purple.

And how do u take it off private browsing?

Same keyboard shortcut ("Ctrl+Shift+P") to get into it, or the Tools > Options > "Start Private Browsing:" or similar (stop or end) to stop it.

See

• Private Browsing | How to | Firefox Help
  https://support.mozilla.com/kb/Private%20Browsing