Of course you can. Pensions are a form of debt. If the state is bankrupt, it's reasonable to trim its creditors. Pensioners included. (The politically-savvy way to do this is probably to spin off the pension fund as its own entity and then default on bonds, which the pension fund would hold alongside others. Then leave it to the pensioners to figure out how they haircut themselves.)
The tax base is mobile in a way expenses are not.
I'll speak to this personally. In April 2021 New York City raised its top tax rates. I'm only moderately wealthy, but that prompted my moving out of the state.
Same as universal healthcare, seems like you net benefit by removing these burdens from localities and businesses.
That's one option. Another is better distributing productive capital. Building public housing so its occupants wind up owning it, for instance.
But that's getting into top-down redistribution at the federal level, which isn't in the cards for now. Within the context of cities and states, pensions are no longer a good idea.