It would be unusual for a charity, of any size, to operate without any reserves. There are, however, some charities where charity trustees deliberately choose to hold no reserves. These charities spend the budgeted income in the year on activities. This can present a financial risk if unforeseen costs may arise. If you are considering not holding reserves you should make sure that you have considered all the financial and other risks.
If you have excess reserves you should consider whether these need to be spent. Charities should spend the money they have to advance their charitable purposes. If you hold excess reserves then you may not be fulfilling your charity trustee duties. If the charity has reserves that cannot be spent on their purpose, because their purpose is too narrow, then you could think about changing your purposes. Do this you need to apply to OSCR for consent.