What is the most I can lose in an uncovered call if I cash out before the expiration date?

Answer 1

If you buy a naked call the most you can lose is 100% of what you paid for the option. (If the option is out of the money you may not be able to sell it before expiration.)

If you sell a naked call the amount you can lose is, in theory, unlimited. It is certainly more than the premium you received when you sold it. In practice, when you have exceeded your margin limit your broker will issue a margin call and, if necessary, close the position for you. In the case of a large gap in the price of the underlying, the loss can be huge, more than the entire value of portfolio.

Answer 2

If you are talking about shorting an uncovered call, the amount you can lose is almost infinite. The stock can keep getting takover offers and can keep continuing to rise, causing a loss of thousands of percents.