For this you need to know the basics of transplanting from pot to pot.
-Take the main stem at the base (Where the plant meets the dirt)
-Put your middle and index finger on either side of the stem.
-Turn the plant upside down holding the bottom of the pot and the bottom of the stem with your two fingers.
-Remove the plant from the pot.
Now here is the extra part for putting it into a hydroponic system.
-Rinse your roots gently with water until most of the dirt is gone.
-Place the roots into your hydroponic medium (Rockwool, Clay pellets, Etc.)
Some factors to consider:
-The dirt will fuck up your water pump if it is unfiltered.
-Replace the systems water continualy for the first couple of days to get rid of as much dirt as possible. The roots grab that shit and wont let go. Get rid of as much as you can.
I would suggest using a DWC system for this since there would be no pump to clog.