I believe this will answer your question:

*"If you created your account with a dot in your username and you wish you hadn’t, you can change your ‘Reply-to address.’ To change your reply-to address:

1. Click ‘Settings’ at the top of any Gmail page.
2. Enter your [email protected] without a dot in the ‘Reply-to address’ field.
3. Click ‘Save Changes.’ When you log in to Gmail, you need to enter any dots that were originally defined as part of your username."*

I believe this will answer your question:

If you created your account with a dot in your username and you wish you hadn’t, you can change your ‘Reply-to address.’ To change your reply-to address:

1. Click ‘Settings’ at the top of any Gmail page.

2. Enter your [email protected] without a dot in the ‘Reply-to address’ field.

3. Click ‘Save Changes.’

When you log in to Gmail, you need to enter any dots that were originally defined as part of your username.