Change bonus depreciation to depreciate the asset through the useful life.

Hi,

I have used bonus option in for the fixed assets which needs to be fully depreciated at purchase in Tax book. Once purchased it is fully depreciated and the net book value is zero .

Now I want to change the depreciation method of the tax book to the same depreciation method as actual (Accounting) book. That means the asset needs to be depreciated same as accounting depreciations. 

I cant remove or edit the bonus field. I did a depreciation adjustment and re-ran the depreciation, but still it depreciates fully because bonus is applicable. 

Is there any way that I can remove the bonus method and let the asset depreciate over it’s useful life?

Thank you,

Dulanjana