How does the Federal Reserve unwind the asset purchasing scheme announced in response to the 2020 Coronavirus Pandemic?
The unwind depends upon what the central bank did.


If the central bank did a repurchase agreement (“repo”) or lent against assets for a fixed time, the agreement automatically unwinds at the term of the deal (which is short). They would need to enter into new deals to keep their balance sheet size unchanged.
If they bought the asset outright, it will either mature, or the central bank can sell ahead of maturity.


There are no “charging a premium” involved; the cost of the operation is embedded in the lending cost (or purchase/sales price of an asset).

There was a very large debate about unwinding central bank balance sheets in the 2010-2016 (?) period. The Fed was eventually able to slowly reduce the size of its balance sheet in the last cycle, and there is no reason to believe that this time is different. There is no sign that an “unwind” was necessary, nor are the effects of unwinding a deep concern.