If you're a heavy Streak user, you may have several pipelines that you work with and several other pipelines that your team has shared with you. The left hand sidebar in Gmail can quickly become crowded and it can be hard to find the pipelines you need to access on a daily basis.

You can hide pipelines that you need to access less frequently by opening up Gmail and clicking on the dropdown icon next to the pipeline name:

Your hidden pipelines are still accessible under the "Hidden Pipelines" label which can be expanded:

To unhide a previously hidden pipeline, simply hover over the dropdown icon on the hidden pipeline and click "Unhide Pipeline".