whether I can spread the remixes, or this violation of copyright? if yes how?
No, it’s not alowed at audiojungle (if it’s a remix of copyrighted commercial recording).
Look here: http://support.envato.com/index.php?/Knowledgebase/Article/View/376/0/audiojungle-and-pastiche-imitation-tracks last line at the list “What do we NOT allow?”
You can upload remixes of your own tracks, or your versions of songs that are in public domain, for example, if an author died more than 70 years ago, everything what he / she has made is in public domain
I can’t wait until 2068 to upload my piano versions of ‘Strangers In The Night’ and ‘Love and Marriage’