If they are moved correctly over to the card, then they would no longer be on the phone. They would only be on the phone if you copied them rather that moving them.
The fastest way to do this is to connect the phone to a computer and open the folder with the files you want to move through the computer. Select them all, select 'move' and then move them all to the SD card. This will leave them only on the card and not on the phone.
Just remember that any app they are associated with will have to now look for them on the card rather than the phone. So you will have to go into the individual apps settings and change the location (if needed).