This is a workplace pension and therefore withdrawals are only available for members over the age of 55 (57 from 2028). Once contributions have ceased you will have two options:
leave pot where it is or
transfer it to another provider.
There are some exceptions to the withdrawal age, for example in case of ill health. (See: https://www.moneyhelper.org.uk/en/pensions-and-retirement/taking-your-pension/early-retirement-because-of-illness-sickness-or-disability). In these circumstances, the trustees will consider each case individually.