Loosen the bolts holding the sink from the wall. Use an adjustable wrench to turn the bolts counterclockwise and loosen them just enough so that you can wiggle the sink a little.
Unscrew the bolts that attach the pedestal to the floor by turning them counterclockwise.
Check the floor beneath the pedestal to see what may have caused it to wobble. A tile may have cracked or house settling may have caused hardwood floors to shift. Taking a peek under the pedestal gives you the opportunity to make any necessary repairs.
Place the pedestal back in place but do not bolt it to the floor yet. Place the sink on top. Insert a wooden shim underneath the pedestal. Place a level across the top of the sink and insert or remove shims as necessary.
Cut off the end of the shim with a sharp utility knife. Reassemble the sink and pedestal. The pedestal's bolts should be snug but not too tight to avoid cracking the pedestal.