Last night I tried to install FormBuilder. After installation the admin layout changed completely to white background and list... like if styles went missing

Then few bugs showed up, such as the one U get when I click on Modules link: "Fatal error: Call to undefined function: restrictunknownparams() in /usr/home/xxxxx/domains/xxxxx.com/public_html/modules/FormBuilder/FormBuilder.module.php on line 149"
The "Module Manager" links opens, however the FormBuilder module does not show as being installed.
The Wysiwyg Editor in "Pages" editing stopped showing.... and many other smaller bugs which are limiting the functionality of the CMS.
I tried to delete FormBuilder via FTP but the server wouldn't allow me to do it. I tried to do it via FileManager in DirectAdmin, same "unable to delete".
Any advice on how at least restore the admin to its previous layout and functionality will be much appreciated.
Thanks!