For most users, storing the Encryption Keys in the browser is the right choice. It is secure and poses no threat to your LoTW certificate security, as no data is stored anywhere other than on your own computer. This is equivalent to storing your LoTW certificates on your own computer.
However, you can delete the Encryption Keys from your browser if you wish. You might want to do this if you are using a shared computer, or prefer not to have copies of your key stored in your browser environment because it is possible other users will access your browser. Before you proceed, please make absolutely sure you have a copy of your Encryption Keys as they cannot be restored if lost.
To delete the browser copy of your Encryption Keys, click the link at the bottom of each page (as depicted below). This button allows you to clear the Encryption Keys completely from your browser.