What is dilution?

Dilution is the reduction in shareholders' equity positions due to the issuance or creation of new shares. For example, if you own 10 of the 100 shares, you own 10% of the company. If the company issues another 100 shares you own 10 shares of 200 shares, thus 5% instead of the initial 10%. You share in the company is diluted.

Selling your shares, which results in less shares in the company, is not a dilution of your shares.