If you look in the lower righthand corner, you'll see some white circles around some round buttons. Click the one that says "All In" or whatever shit they named GWM. That will disable the -5/+10.
yes, you were right, it was the 3rd circle (had to go to 2nd page
) Great Weapon Master: All In
hmm.. i don't know if can disable this thing, i'm clicking on everything that's there doesn't do anything, so all the feat will have description there then
Much appreciated for pointing me it the right direction