Once you've finished creating your plan and you are ready to share or export it from your Planner, click the ••• menu button and then select Export plan from the context menu:
Note: Any empty rows or columns within your Plan will not be included in your PDF.
You'll be prompted with a dialog where you can select what to include or exclude with your export. Additionally, you can select if you would like to download the PDF to your own computer or have it generated and emailed it directly to your client:
Once you have customized your export, click the Start Export button and your PDF will be generated.