For starters, can you clarify why you think depreciation is to high? It would also help to know what the asset is.
if you have been depreciating an asset for 2 or more years and have a valid need to change it, you can't just "change" it in year 3 or later. Under no circumstances and with no exceptions should you ever change anything dealing with depreciation in the TurboTax program. Doing so completely skews the depreciation history, which will make your "new" depreciation wrong also. Then, that's basically hanging out a sign to the IRS begging them to audit you yesterday, if not sooner. Lets not go there.
If the depreciation has been wrong for two or more consecutive years, the IRS has a specific method using IRS Form 3115-Change in Accounting Method, to fix it and make things correct.
So what tends to make you think depreciation is wrong? Let's confirm it's wrong before pressing any further. It may not be - unless you are renting out a percentage of your residence, or some other property that is less than 100% rental use.
