Ah yes a PowerPoint is a zip file of a silly size you can rename it to .zip open it up click around the folders within find that stupid massive file, say like a .mp3, hidden within, which is inside the PowerPoint but might be hidden inside the template of the PowerPoint but not used. Delete it, save it, rename it back to PowerPoint and it's not 50mb but 1.5mb.
Great thing to do to if you want to send and share your PowerPoint presentation. Don't save, instead Save As a PowerPoint picture presentation, as that will remove all the template, unused pages/slides and images or random videos within the PowerPoint presentation.
That makes it much smaller and removes unused things that might contain company information within the PowerPoint presentation template.