What shock is it on the bike?
I’m gonna guess it is a Fox shock.
If so you will need something like THIS TOOL for removal, re-installation of the bushes.
And THESE BUSHES would be like for like replacements.
If the top hats (metal mountings) for the shock are worn you should look at replacing these as well, most good suspension tuning/repair places should be able to sort you out with them – Mojo, TFTuned, LoCo etc