Replace the caster wheels with stationary glides
Use wheel stoppers or caster locks
Place non-slip pads under each wheel
Remove the wheels and install fixed feet
Wedge the wheels with rubber or wood blocks
Use a chair mat with a grippy backing
Apply wheel brakes if the chair supports them
Put the chair on a rug or carpet
Tighten or adjust the caster stems
Use furniture cups under the wheels
Add adhesive rubber feet to the base
Clamp or strap the chair in place
Fill the caster sockets with fixed inserts
Replace the chair base with a non-rolling base