I managed to make them disappear in the site and site collection features list by deactivating (and then delating) the solutions the SOLUTION I used to deploy them in "Site Settings" -> "Galleries" -> "Solutions". Deactivating the solution means deactivating features too. After the deactivation of the solution, the gray "Delete" button for the sollution is enabled. Then delating the solution help uninstall the feature from the site collection.
Even I seem to achieve whatThe "Ambiguous match found" I want, I'm not sure this shoulb be the right answerencountered was caused by errors in my code. JustIt has nothing to give anyonedo with similar problem a thoughtnot completely deleting the solution. More answers and explanations are still welcomed :)