The whole purpose of the SCROG is to keep your plant all at the same level so you can move your light closer. Once you tuck a part of your plant you just leave it there at the screen level. If you release it, it will pop up above the screen and defeat the whole purpose. If that part of the plant pops back up just tuck it back to screen level again. Then as countryboy suggested remove new growth below the screen after flowering begins, so all your energy is going to producing fat buds.
There are many youtube videos if that would help. Just search SCROG or screen on green