Fatal error: Cannot redeclare class TC___ in

Bad decision who suggested you that? Cannot remove the child-theme functions.php with ftp?

Use FileManager to delete the functions.php from your child theme and everything should be okay. You aren’t supposed to copy the entire functions.php from the parent to the child theme; both the child and the parent theme’s functions.php will be loaded automatically. What are you trying to accomplish?

I think she cannot access to the dashboard, because of that error in functions.php .
Do you have any access to the db instead?
If yes, would you consider to try this?

https://www.inmotionhosting.com/support/edu/wordpress/change-theme-in-db

I think she cannot access to the dashboard, because of that error in functions.php .

She needs to use FTP into your site (or whatever file management application the host provides).

Do you have any access to the db instead?

We do not have any access to your site or database. If you feel that you require that level of support, please consider hiring someone instead.

esmi… thank you very much for your advice!!! I used FTP and deleted the folder functions.php. Then I created a new empty folder.
Now I have my website again.
Thank you!!!