Not able to open the product edit after disabling or removing the extension. What can I do?
The extension adds several attributes to your attribute sets. For the 'et_yml_offer_type' attribute to function the extension is needed.
To be able to enter the product edit simply delete this attribute from your system (Catalog -> Attributes -> Manage Attributes) or remove the attribute from the attribute sets (Catalog -> Attributes -> Manage Attribute Sets).