Adobe reader even showing very old deleted files

Hello,

My issue is that there were pdf files on my phone which i downloaded and even deleted long ago. But i was surprised to see those files when i opened adobe app and clicked on "files" tab. There i can see and even open all those deleted files. I dont want those deleted files. Its just a clutter for me. Why are those deleted files there in the first place and what should i do now in order to remove them ?