There is no way to set the accumulated amortization (depreciation) to an arbitrary amount. The ROU asset can be set to a specific amount, and it can be reduced by an impairment of any amount, but the accumulated amortization is mathematically calculated based on the ROU asset, previously taken amortization and impairments, the amortization methodology (usually straight line for finance, interest method for operating) and the remaining amortization life.
Using an impairment would work only if the accumulated amortization balance should be increased (net asset reduced) and the lease is finance; if it's operating, a partial impairment causes amortization to change from interest method to straight line.