Depending on the mainboard you are using - assuming its something like an SKR Mini E3, then leaving it as the CR10 display is fine. It’ll output on the EXT port - but you don’t have to have anything plugged into that - unless you want to use the TFT display in Marlin mode - but that depends on your model of TFT35 - as not all are made equally.
If your display supports Marlin mode, I believe it has a second cable that can connect to the EXT port.