Legally you must be 16 years of age or more to execute your own Deed Poll in the United Kingdom and over 18 years old in Northern Ireland.
Someone with parental responsibility can only override your wishes in exceptional circumstances and not just because they don’t agree with your choice. If, however, there is a court order in force forbidding you from changing your name, you’ll have to wait until you are 18 years old.
In general, children under the age of 16 years (in the UK) and under the age of 18 years (in Northern Ireland) can have their name changed by anyone with parental responsibility for the child, provided everyone with parental responsibility agrees.
NameSwitch does not currently offer a Deed Poll service for anyone under the age of 18 (in either the UK or Northern Ireland). This is in line with our general terms & conditions of use.