How to add folder in polaris viewer?

You should first unhide the folder using view hidden files mac. Than, after unhiding files, you can easily delete folder. 

I want to delete folders from apps I no longer have like golauncherEX but I can't because of hidden files. How do I delete those folders? Anyone know? 

... was not it. There is a folder /sdcard/.Mail for attachments and ... shell to cd into the folder and rm * the files). I think ...  

There is a reason why some files are hidden. They are meant to be left alone because messing with system files could make the operating system unusable, just like in any other operating system Windows ...