By default, Voyant is setup with a tax-free cash limit of 25% for pension withdrawals. This limit however can be raised on the Taxes screen. Click on Taxes on the left sidebar, select the 'Pension Lifetime Allowance' option, and enter the increased percentage in the 'Maximum allowed tax free cash %' field.
Note, raising the maximum allowed tax free cash on this screen raises it for all pensions.
Once the limit is changed on the Taxes screen, you can go to the Pensions screen (Pensions > Money Purchase) and increase the tax free cash for a selected pension. Highlight the relevant pension in the Ledger on the right, open Withdrawals & Annuity > Crystallisation of Money Purchase and change the 'Lump Sum' setting either by amending the % value from 25 to the higher value, or by changing it to 'Tax Free Cash Only'. If you choose the 'Tax Free Cash Only' option, the software will apply the tax-free cash percentage from the 'maximum %' value you entered on the Taxes screen.
Once again, if you change the maximum tax-free cash on the Taxes screen it will apply to all pensions owned by this person in the plan. So for the other pensions, if there are any, you would need to go into each of their input screens and set them to only take 25% of the funds to be crystallised in lump sum as tax free cash.