change from full screen in mac finder to normal

Use the control+command+F keyboard shortcut to exit full screen. Resize the Finder window to the size you want to see in future Finder windows, because it remembers the last setting.

Try rebuilding your Finder preferences:

From your Finder "Go" menu > "Go to folder" then copy & paste this file path:

~/Library/Preferences/com.apple.finder.plist

Click Go.

Delete the plist file.

Then, restart, or log out and in again.

(You may have to reset some Finder preferences the way you like them)

Are you actually in Full Screen Mode or have you just maximised the window, in any case press the Green button.

The control+command+F keyboard shortcut has been available for years prior to El Capitan and testing it in El Capitan Finder works as expected for me.

Something to try. Might be a corrupt .plist.

Do a backup, preferably 2 backups on 2 separate drives.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J.  When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder.  Select Library. Then go to Preferences/com.apple.finder.plist.  Move the .plist to your desktop.

Re-launch Finder by restarting the computer and test. If it works okay, delete the plist from the desktop. Then reset your preferences as desired.

If the same, return the .plist to where you got it  from, overwriting the newer one.

Thanks to leonie for some information contained in this.

Drive your mouse to the top of the screen to reveal the toolbar, then go to View menu > Exit Full Screen.

Safari shouldn't affect it. Try Force Quitting Finder by going to the menu/Force Quit or command - option/alt - esc.

Not on Finder menu but at the top of Finder window, just below the Apple.

Show us a screenshot of what you see, when you forced quit Safari and opened it again did a new window open.