Deleted fitbit from my cell phone. reinstalled. when I attempt to set up again using my email address it says an account for this email already exist

start a new account there.
we cant,

Instead of choosing "create an account", choose to log-in to the existing account instead.

In an article titled, "Email already exists," at: https://support.google.com/accounts/answer/69849?hl=en

Google Help advises:
If you see this message when you try to create or change your account username, it's possible that you've already created a Google Account with that username. It's also possible that someone else accidentally entered your email address when creating a Google Account, but was never able to verify email ownership.
To reclaim your Google Account, please follow these steps:

1. Visit the password-assistance page.
2. Enter your username (your full email address).
3. Type the letters shown in the distorted picture into the appropriate field.
4. Click Submit. You'll receive a message at the address registered as your Google Account username. Follow the instructions in this message to reset your password.

After you've regained access to this account, you can either delete the account, or change the username on the account to another valid email address. You'll then be able to change the email address on your other account to this email address.
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I hope this works for you!

It's so because you already have a google account!!
Instead of creating a new account using the same name, use your already existing account to log in to your new phone.

2. In the gmail account go to Settings >> Forwarding and POP/IMAP then check Enable POP for all mail.
3. Delete any existing email accounts from the phone, then go into email.
This will prompt you to set up your mail.
4. Enter her gmail address (e.g. [email protected]) and password, then continue
5. Enter your whole email address as your user name, continue
6. Select POP
7. Enter the following as the pop address: pop.gmail.com

Please provide the model number of your device, and what if anything you tried, do you have access to the the settings? In short reguardless of what platform you use (I.E apple rim android etc) this process is generally almost the same,
Try to navigate to your settings and find to email or accounts withing your settings- under the setting in sub menus look for "add account" or "add email", if you do not see this anywhere in any setting sub menu then go to next try
Try to navigate to email and in sub menu or setting attempt to locate "add account" or "add email" if you do not see this in any sub menu see below
Try mail icon, then click options, click email account management, select [email protected], a menu pops up, select delete account, start over and use same method to add [email protected] to the device
Ok so this means you did not find it in such event if you provide me with a model number I can give you a step by step guide, I attempted to show you how to add an account as for some platforms do not allow you to change the primary email address of the device without a hard reset of the device, only to add addresses but you can add accounts and disable receiving mail from that account,even change the password to stop the device from getting emails, but give me your model number and I may better assist you--Good Luck.

I had this problem, I am not 100% on what fixed it but try this:
In email:
* menu -> accounts
* menu -> account settings
* Its my gmail, so I selected google.
* next
* Sign in
* Enter the username and password for your existing account
* It will say "Account already exists; There is already a [email protected] account on this phone". But as soon as it said that I started getting emails again. So I am assuming that it updated the password.

Attempt to reset your password on the facebook as missing password. then reconfigure the secret passes into another pass, maybe phone.