If you have been auto-enrolled then you have the option to opt-out. If you opt-out within one month of being added to the scheme, your employer is obligated to refund you any money you’ve paid in. To opt-out you will need to contact the pension provider.
If you opt-out over a month after being added it is unlikely that you will receive any of the money you have paid back and this will remain in the pension scheme until you retire. In this case, if you have a personal pension, you may be able to transfer the payments in your workplace pension over to your personal pension. Similarly, you can also do this if you were enrolled on a workplace pension at a later date.