how to remove the square box (right side) in the drop down . by css

Please provide a screenshot of what you are talking about.

https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

It is best to use a compressed image type like PNG or JPG to save the screenshot and make sure that you do not exceed a maximum file size of 1 MB.

Then use the Browse .... button below the Post a Reply text box to upload the screenshot.

the drop down box consist of white rectangular box ,

i dont need that white box.

i need oly the down arrow ,

how to style by css ..

.selectclassname{border:none;}