1. Go to the 'Security Settings' of your account and click the 'Change E-mail Address' button.
2. Enter the new e-mail and your MyKNX password in the respective fields. Then click the 'Next' button to complete the process.
3. If the new email address is not linked to a MyKNX account, then it will be changed and you will receive the following confirmation message.
Else, if it's already linked to another MyKNX account, then it's better to reset the password of the other account to gain access again.