At the time of forfeiture, the share capital account is:

When shares are forfeited, the Share Capital Account is debited with the total amount called up on those shares till the date of forfeiture, because the capital is being reduced by that amount.The entry is:
$$\text{Share Capital A/c (No. of shares }\times \text{ Called-up value per share)}\text{Dr.}$$
$$\text{To Share Forfeiture A/c}$$
$$\text{To Calls-in-Arrears A/c}$$