Shimano 6 speed cassette.

[Paulus]

What I thought was a 6 speed freewheel, seems to be a cassette , I can see the end of the spines by the wheel hub.
The lockring is bigger than any cassette removal tool I have.
Any ideas on what tool to remove it.
It has cleaned up well and sounds good, but in case I need to remove it in the future. The only clue I can see is LG on the smaller sprocket.
By the way, the axle bearings are now cleaned and are back in.

 

[midlife]

The smallest cog locks the others in place, removal of the cogs needs 2 chain whips. Looks like Uniglide.

Removing the freehub itself is axle out and big (12mm?) Allen key.

Sheldon Brown covers it well

 

[LittleWheelsandBig]

Most of the 6sp freehub bodies were held on with an Allen bolt needing a 10mm Allen key but a few were pressed on and a couple were just held in place by the main bearings. Your freehub might not be one of the first type.