How does this ribbon cable connector open?

To replace a switch plate on this Canon Lens, I need to remove the ribbon cable from the brown and white connector in the lens.

This type of connector is probably used in other electronic equipment so even if you have not disassembled a lens, you may know how to open this connector.

Photo 1 shows the ribbon cable of the part I need to remove locked into the brown and white connector.

Photo 2 shows a side view of the brown and white connector.

How does this ribbon cable connector open? Does the brown part slide down in photo 1 toward the ribbon cable or does the bottom edge of the brown part lift up to release the ribbon cable?

Photo 3 show the new switch plate with the attached ribbon cable.

Photo 4 shows the new ribbon cable with the conductors exposed near the end.

The lens was first sold in September 1999 so the connector is of that vintage.

Canon said there where no instructions available when I ordered the part.