Can I deduct the expenses from buying a mobile home to rehab and sell. It has not sold yet.

No.  You will need to wait until you sell the mobile home to deduct the expenses.  You will then add these as the cost basis of the home. 

When you do sell it you would enter the sale of the mobile home by clicking the following:

• Federal
• Income
• Show More next to Investment Income
• Start next to Stocks, Cryptocurrency, Mutual Funds, Bonds, Other (1099-B) 
• Select Other
• Continue through and select Other again for the type of investment
• Answer that you purchased it
• You will need to enter the selling price, dates and the cost basis which will include your rehab costs, purchase price and then you will also enter your selling expenses.