This means that is a profile registration started for the email you want to change to. The choices you now have is as following:
1. Complete registration of the new profile (most likely you will get an error on phone number because that is already in use in another profile) without adding phone number. It's not a mandaory field and our communication goes through email.
2. Choose if you want to continue having two profiles (ex: one for private and one for work), if not, scroll to the bottom on your profile under the section "profile" and delete the new profile.
3. Now you can add the work- email to your "old" profile because there is no other profile connected to it.