How do i classify payments to a individual 401k? I am small business LLC that utilizes guaranteed payments and not payroll to pay myself.

I'll throw something out and see if it makes sense to you. In many ways, what you do in QBO doesn't matter as much as what your accountant does with the information. So you could set up an account for those payments in a number of ways, and your accountant will just take that total and put it onto your tax form in the correct way. You could just put it under payroll expense if you want.