Fitting a 40t expander on sram and removing the 11 tooth…how?

Just looking at getting a works components 40t expander for sram cassette and noticed on their site it says;

“To be used with 10 speed SRAM X5 11-36T (PG-1030), X7 11-36T (PG-1050), X9 11-36T (PG-1070) cassettes with the removal of the 15 or 17T cog and associated spacer. You are also able to remove the smallest cassette cog and replace the lockring with a suitable size.”

So what do I need to remove the 11t cog and fit the lock ring? Is it a special item and where can I get one?

I know doing this isn’t really expanding my cassette but just lowering the gearing, however I’ve just recently fitted a new 34tooth n/w direct mount ring on a bb30 crank, gearing is a bit tall and the expander is the cheapest option without replacing it with a 32.

Is the expander cheaper than a 32t? Plenty to choose from at similar prices. Especially after you buy a lock ring tool and chain whip.

Got all the tools, £26 for expander, £45+ for direct mount ring plus bb30 type are hard to find.
In fact their cheap at works components but never in stock.

Superstar do a 12t lockring in a variety of colours. I’m not 100% if it will fit on a regular cassette though, but should do.

Why would you want to lose the 11T? Surely that completely defeating the point of a “Range Expander”? You’re just adding 10% at the bottom and taking away 10% at the top!

Speeder, like I already said, dont mind losing the 11t, cheaper than trying to find a smaller direct mount bb30 ring.

Absolute black do a special lockring for dropping the 11t ring, might be Shimano only though. £14 inc postage direct.