This window lets you unjoin Parts.

This method of unjoining Parts works well no matter how many Parts you have in your model.

If you only have a few Parts, you may prefer to use a Matrix to choose the Parts you join (or unjoin)

Select Part(s)

This box lists all the Parts in your model. Select one or more Parts in this list.

Select Part(s) to unjoin to the above list

This box also lists all the Parts in your model. Select one or more Parts in this list.

Press   to unjoin all Parts selected in the top window with all Parts selected in the lower window.