I have a vintage Shimano 105 rear wheel with a 6 speed cassette ( please refer to photo below ). It is definitely a cassette because the lock ring turns when you spin the wheel ( I found this out in the Park Tool website and besides, I could see the slots on the hub when looking at the back of the cassette towards the spokes). Does anybody know what type of lock ring tool is needed to take this cassette off? I went to a an LBS nearby ( MEC here in Canada ) and they don't have a tool for it and can't figure it out either. Park tool website does not have a tool for this one either. Thanks.

Two chain whips.

Uniglide cassette, the first cog is the threaded lock-ring. Chain-whips to remove it, the rest of the cogs slide off.

Thank you both for your replies. Makes sense. Thanks again.