"when will they be deleted from my brokerage account and the capital gains loss appear? Or will they continue to remain in my brokerage account indefinitely until I do something with them"
How would we know? We don't even know who your broker is or what country it's in. Shouldn't you ask your broker?
Offhand, I'd think the zero valuation would remain for a long time. Otherwise some investors would wonder what happened to their RSH shares.
As for taking the loss on your taxes (RSHCQ became worthless in 2015), ask your tax advisor and not a stock bulletin board best known for scams.
I will repeat what I said a year ago: Smart investors dump deeply troubled investments early on... when they still have some flexibility.
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Because the Good Life is Just a Pump or Two Away