Please can someone advise the correct way for me to account for this refund:

In May I purchased an iPhone for £459.99. This went on to May's VAT return and I reclaimed 50% of the VAT due to it being for personal and business use.

This week I have returned it for a full refund. There doesn't seem to be a simple way to reverse the money out transaction and I want to ensure I'm doing this correctly, especially because of the VAT.

Thanks!