Use the Hide/Unhide function to hide (or unhide) a part reference that you select. When a part reference is hidden, its visual representation is replaced with a bounding cuboid that retains the color attribute of the hidden part reference. If the part reference had not been assigned a color attribute, it will take on the color set for Hidden Part Ref Box under File>Properties>Settings. The cuboid is aligned with the world axes of the referenced part. Hiding is primarily useful to reduce confusion when complex geometry is visible in the viewport.

Hide-UnHide using Part Splitter Reference tab:

The reference currently highlighted will be hidden when the function is first selected in the Hidden tab, and a checkbox will appear beside the Hide function in the right click menu and Part Splitter Reference tab for that item. To un-hide the reference, simply select the Hide/Unhide function a second time. When using the function from the Menu, you must select the reference.