How can I remove cmd+shift+left/right shortcut in Finder?
In System Preferences select Keyboard, then the Shortcuts tab. Click App Shortcuts in the left column, then the + button. Next you will change the Application to Finder, Menu Title to Show Next Tab, and the Keyboard Shortcut to whatever new you'd like. 

Keyboard Shortcut can be anything you want, but I might recommend controlshifttab (for Show Previous Tab) and controltab (for Show Next Tab).



Repeat the steps but change the Menu Title to Show Previous Tab for the other shortcut