I would cold-heartedly agree with the first post. The best way to check your grammar is to have somebody else proofread your paper for you. For the sake of completeness I will add that there were two old Unix tools for checking writing: style and diction.
I personally have never used them.
Removing LaTeX is fairly easy with sed for instance but there is a tool called detex which will do exactly that for you. However it is not 100% successful and I would still suggest that you read text document.