Change of email address

Hello,
I was changing my email address to "***", it was saying that is taken. Well, that is my User Id in most of my account. I'm 70 yrs old and just want to uniform User ID so it's easy for me to remember. If you need proof, either you can investigate my other accounts that's in fact myself, or ask me my identification or other questions. I'm just preparing before I fall into Alzheimer's disease or dementia. I'm starting to feel that it's difficult for me to remember different User Id, bad enough with the passwords. I do most of my transactions online. So please help me. I want to change it to ***@***, please help me... Thank you very much.