To what extent can you change a conference article after review, when implementing reviewer suggestions makes the paper too long? I recently submitted an article. After review process, I added all suggested changes to the article and now it is longer than formatting restrictions allow.

It is a conference article and any extra pages are charged. That extra page contains only some references. My question concerns the extent to which I can modify my article after receiving review. I am not talking about results or conclusion or any other major topic related changes, only e.g. grammar, style, figure location, text and section rearrangement,  layout, etc.).

Can I remove some of the suggestions of reviewers? To what extent are any other (non-required) changes acceptable and/or permitted?
Within the guidelines set by the conference publication process, I see no reason why you can't make small changes that can reduce the page size. I will often edit things down for the final version to fit in the desired format. Of course, if your review comments were "everything is too terse, please expand", then you might have a problem with complying with review comments and page limits :)