That's a bit of a loaded question. Generally speaking, every user has an equal voice. You can upvote or downvote each poster once. So your own vote might not be enough to move your favorite poster to the top, and that's the way it should be. Mods only override the popular vote when needed. The requirements for the primary poster marker are in the Contribution Bible.

Hello, how can I delete poster? Thx. Best Regards

Hello, how can I delete poster?

Use the report button on the entry (Overview -> Report) to report the poster as an incorrect image. Please add a link to the poster and explain why you believe it should be removed in the extra details box.