I’m trying to create something on blender but I opened this command bar by accident. I got out of it after a few minutes but now it’s stuck there.
See https://blender.stackexchange.com/a/5633/1245 about closing redundant and unnecessary editors windows in Blender. Tl;dr is find 2 opened editors of the same size with divider between them, hover mouse over 3 lines in the corner and drag it towards another mentioned above editor. Another way is right click on the divide bar and choose Join Area.
Although I’m only guessing about what exactly are you trying to close.
what is “it”? stuck where? Jpeg screenshot doesn’t show what did you try to drag, where and what you try to close.