The latch is on the white case. The tabs are on the gray case. You will be pushing the white latch AWAY from the gray tabs.

Put your flat blade to the OUTBOARD side of the white latch in the hole. Push INBOARD to pry it OFF of the tabs, pushing down through the hole at the same time in order to push the white case off. You'll want to hold the router by the gray if you can.

As you push the latch you'll obviously need to try to pry the two pieces apart like with your fingernail.