Yes you can move it your self or get a contractor to move it for you.
There is no law to prevent you from doing that and Openreach or BT will not have any idea where every master socket was installed in every property in the UK.
All you need to be aware of is that if you move it and something goes wrong and causes damage or problems with your connection or the Openreach network you will be charged the cost of repairing it.
Are you a BT Retail customer with BT broadband?
The problem is that there is only about 10cm of available cable and the cable needs extending
If you do an Internet search for "Moving BT master socket" you will find plenty tutorials how to do it or if you do not feel confident doing it your self you could employ a telecom engineer to move it for you.