We don't "render" tracks in Pro Tools, we "print them."
Set the output of the track you wish to "render" to a free bus. Create a new track (name it "BD PRINT" or "GTR_PRINT" or whatever) and set that new track's input to that same bus. Arm it to record. Place a marker to indicate the beginning of your song (another for the end is also nice too...this is to ensure your files are all the same length and have the same starting point.) Highlight from the 1st marker to the 2nd and push record. Wait. Repeat for each track. You can "print" as many tracks at a time as you have free voices/buses in Pro Tools. Go to your project folder's audio folder and sort by date or file size to easily grab all the files.
I also do this to Instrument tracks with memory-intensive virtual instruments to free up memory if needed and to Drumagog tracks (I like to visually verify the hits are lined up.)