In Acrobat : File - Save As Other - Reduced Size PDF...
In Acrobat Pro DC: (Do anyone of the option)
1. File>Save As Other > Reduced Size PDF
2.File>Save As Other > Optimize PDF
3. Ctrl+Shift+S (File>Save As) > In save as type: choose "Adobe PDF Files, Optimized(*.Pdf)" and click on for image settings to your desire.
4. Click on "Tools" tab and choose "Optimized PDF", on the optimize properties choose Advanced Optimization and do your desire set up or click on Reduce File Size