Remove the tiny diameter cross pin if it uses one and press straight down hard on the nose of the ramp.
After it sinks down far enough you will be able to move it rearward and remove.
The spring tension is considerable, so a helper to hold the rifle or better a soft jaw rifle vise makes all the difference.
I've done it many times and it can be a bitch, so use a soft vise or the rifle will slam over on it's side when you push hard enough to depress the spring.