Haven't been able to figure it out on the mobile apps. Maybe it's just not a feature yet. I've been able to do this on other PDF mobile apps.
Create a copy of the file and delete unwanted pages.
If you have a paid subscription of Acrobat Pro Dc you will be able to unlock some premium editing features.
In the full desktop version of Acrobat Pro DC you extract pages through the "Organize Pages" Tool.
That feature is not available through the Organize Pages tool in the mobile app but, as mention by Bernd_Alheit, you can make a copy and delete the pages that you don't want in that copy.
However the best approach in the mobile app is not through this method.
You can perform a similar page extraction function in your device by opening yor PDF document in the mobile app then select or tap on "Print".
Print to PDF actually allows you to save a document as PDF and only print the pages that you want. This is similar to extracting pages. You'll notice that each page will have a yellow checkmark icon.
Tap on each checkmark corresponding to the pages that that you don't want to save as PDF (the icon will turn into a minus ("-") sign when you perform this action. When you're done just tap on the "Save as PDF" (yellow iconwith a download arrow in white--upper right corner of the working space)..
The next screen will bring you to the "Save to" screen . Select a directory (or folder) for this new PDF and you're good to go.
Info: printing the file will remove all interactive features
Thank you for clarifying that.