LLC revenue should be a return of capital

If the LLC has income, the income will be your income.  An LLC is a flow through entity, this means, that even if you do not take a distribution of the revenue received, you will be taxed on it based on your percent of ownership of profit. You cannot avoid this by claiming that the money you had is a return of capital on the K-1. 

Distribution of retained earnings and return of capital is done in the balance sheet and retained earnings section.  This will NOT affect your taxable income at all.  

The only way this would not be the case is if your LLC elected to be treated as a C-Corporation.  If it did, then the company would file a form 1120 and be taxed on the income.  Then when the income is distributed, you would pay taxes on it a second time.  

If you sold land you would report this disposition by selecting Federal Taxes>>Income>>Dispose of Business Property. When you do this, you will see a list of assets you have already entered.  If you did not already enter the land as an asset, you would select Asset not listed, then list the asset, then dispose of it. 

If you had multiple properties, you would have to list them separately in the asset section in order to sell part of them.  You cannot just adjust the basis without reporting a sale when the land was sold. 

if you sold capital assets then that's where you report the sale for each that was sold. if you expensed them your tax basis is zero so you can just record the revenue as other income.