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.
You Got amount will be recorded in the Customer Ledger.
You Gave amount will be recorded in the Vendor Ledger.
Step 3: This is how recorded payment will look like: