Yes, you would just need to go into Account Settings >> Company Settings and switch off VAT accounting. This will have no affect on any pre-existing VAT records, it will simply ensure that going forward all sales are entered without VAT.
If you wish to calculate a final VAT return through QuickFile after the 30th, you may need to temporarily turn the VAT option back on, file the VAT return then switch it off again. I believe the VAT returns are accessible only when VAT accounting is switched on.