Hello, we will explain the 2 topics:
1. Solve Virtuemart error after installing a language in Joomla.
This problem occurs because virtuemart saves the names of categories, products, etc. in a table for each language, so when you install a new language in Joomla virtuemart will look for this data in a table for that language and when it does not find it, it sends the message, the solution is simple, you just have to install in virtuemart the same language that you installed in Joomla, this language is downloaded from the official virtuemart page, then from the virtuemart configuration select that language by default for the store.
2. Uninstall Virtuemart.
If you do not want to use virtuemart you just have to go to: System >> Manage >> Extensions and search for the word Virtuemart, from the results you must first uninstall Virtuemart_allinone (Administrator - Component), then all the extensions that appeared in the search results (if any cannot be left), then Virtuemart (Administrator - Component). Then in the search box type VM and uninstall all the results. Finally search for TCPDF and uninstall the component. If there is any extension resulting from the searches that could not be uninstalled, let us know.
Regards