I got a Cyclo sprocket remover (chain wrench thing) for £9 from Halfords.
I'd avoided buying one for years 'cos I thought I'd never use one more than once, but it has come in handy a few times since.
Much easier to take a sprocket off and disassemble to clean, rather than poking around with a toothbrush/rag when it's still on the wheel.
I just remembered I used an old bikechain once, and wrapped on old towel round a loop of chain I held onto (otherwise it'll cut into you).
Got the sprocket off eventually but I almost buckled the wheel in the process - far better to get a tool if you want to save the sprocket, sometimes they're stuck on REALLY tight.
Park Tools do a fancy version if you want to spend a ton of money, but the Halfords one does the job.
