No, there won't be any tax when you convert it to a personal use space.
When you sell the property, that is when taxes may be owed. At that time, the depreciation will usually be taxed at 25% (plus state). The rest of the sale depends several factors, including if the basement rental was a separate living unit or not.
When you do convert it to personal use, then for TurboTax, you just go through the introduction to the Rental section and each "Asset" to indicate it was converted to personal use. That will stop the depreciation.
