Mozilla Thunderbird with Eset

Hi In attempting to uninstall Mozilla Firefox and when cleaning up after the uninstall process using windows search/ccleaner/registry finder and cleaner etc (seperate search for both mozilla and then firefox) I discovered Eset/Mozilla Thunderbird but could not delete? - Program files/Eset/Eset smart security/Mozilla Thunderbird (seemingly protected by Eset)) What is the connection and for what purpose? and should these files still be removed.
thankyou

 

Those files are a part of ESS - used for Email integration into Mozilla Thunderbird - and should not be removed.

 

Thanks for info ... should I then un-tick the option (mozilla thunderbird) found in advanced mode - email client intergration. best