Auto-enrollment in a 401(k) does not require explicit consent. However, the employer is required to allow you to opt out: https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-automatic-enrollmen...
The distribution is subject to ordinary income tax. If you are under age 59½ and you do not qualify for a penalty exception, the distribution is also subject to a 10% early-distribution penalty: https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-tax-on-early-distri...
