On all devices, in Adobe Acrobat mobile (iPad, iPhone, etc.) and on Acrobat on Mac and PC, sharing files with the Adobe Document Cloud is optional.
For example, on my iPhone, I can click a small icon of a device with a checkbox at the top of the screen, and there is an option to "Turn Mobile Link Off"
Same on Acrobat DC. Click on Home and at the bottom of the screen Mobile Link has an on/off switch.