Help with Optimization toolbox

I use 'fitlm' fitted two linear models, y1 and y2. y1 and y2 are both responses of 5 variables, x1 to x5. I now have both fitted models in my workspace and I want to optimise y1 with constraints on y2.

For example, minimise y1 while 5<y2<10.

I am trying to use optimisation toolbox to achieve this but honestly i have no idea how to do this.

Please help on this please.