Financial Aid refunds (stipends) are meant to be used for school related expenses. A few examples of school related expenses are textbooks, internet usage, or a new computer. Financial aid is only available for students who are actively taking courses.
As a result, withdrawing from a class can impact both your financial aid and refund.
Keep in mind that refunds are caused by an excess of financial aid that may include student loans that need to be repaid after finishing school. If you receive excess funds that you do not need for school related expenses, you may contact your loan lender to set up a payment with them to return some of the unused funds.