But in practice, do teams actually do this regularly? More importantly, does your manager recognise this as "work"?
Or does it mean: code deletion is good when other people so that I don't have to but I don't invest my time into it? Like technical documentation.
Most places I've worked (> 20 years) regularly delete dead code. Not all the time, but often enough that it's not a problem.
Tech docs on the other hand seem to still kick around. Mostly I read the Tests these days. This tells me the why, and how better than any doc I've ever seen. And they're up to date.
This makes sense.
I regularly encourage my teams to delete code that has no use in the near future. Because every line of code in the production environment leads to maintenance effort, so this would save their time.