If you want to record a payment without linking it to a customer or vendor, please do so from the payment section.
To do so, please follow the steps mentioned in below article.
Step 1: Click on Timelines under Payments.
and click on Actions under that you can select You Got/You Gave for which you want to record the payment.
Step 2: Enter the amount you want to record and choose the payment mode.
Now, Click on Add Payment.
Step 3: This is how recorded payment will look like: