How do I delete the cells in the cell view? I made a mistake and It won't let me delete them. Right clicking and pressing delete does nothing. What's wrong?

Is it a cell you created yourself or one already in game and you just changed ? If it is a modified cell, deleting it will do nothing, it will be restored with the modification flag each time you open the geck. If it is one you created it is not removed bu flagged as deleed and will continue to appear until you clean your mod

Anyway, if the geck doesn't allow you use FO3Edit and select your mod. You'll see everything it changed. You can then delete your cell here. Right-click on it, and select remove. It will ask confirmation and will delete it forever. Be sure you remove it in your mod, not Fallout3.esm

Alernatively, in the geck, in he data selection window you can click on details and see everything you changed. Find the cell, press delete and i will tell you the change will be ignored. It will e removed for good next time you launch the geck

Thanks.