This issue is resolved in the October 13, 2015 release of Acrobat DC. While installing Acrobat DC, now you have the option to keep or remove the previous version (XI or X) of Acrobat.
If your previous version of Acrobat is removed, follow the steps below to reinstall your version of Acrobat. If you can't find the original Acrobat installation discs, you can download the installer of several earlier versions of Acrobat.
If you purchased a subscription to Acrobat XI Pro, the upgrade to Acrobat Pro DC is free. To continue to use Acrobat Pro DC, click Activate in the Tools pane and enter your Adobe ID. If you want to revert to Acrobat XI Pro, follow the steps below.
Creative Cloud member?
If you have Creative Cloud and want to revert to Acrobat XI Pro, see Acrobat DC uninstalled Acrobat XI | How to get Acrobat XI back.
If you purchased Acrobat (rather than subscribed), you need your Acrobat serial number to reinstall your version of Acrobat. To find the serial number, follow the steps below to sign in to your Adobe account.
If you subscribed to Acrobat XI Pro, you don't need a serial number to reinstall. Instead, you'll activate your subscription using your Adobe ID (your email address). Skip this step and move on to 3. Install the previous version.
In the Registered Products list, note the serial number for the version of Acrobat you want to install. You need this number during installation.
If you did not register Acrobat, see Find a serial number.
How you install depends upon whether you have the original discs, need to download the installer, or have a subscription to Acrobat.
If you have the original installation discs, insert the first disc, and follow the onscreen instructions to install.
Acrobat XI Pro
If you purchased a subscription to Acrobat XI Pro, download the installer from Download Acrobat products. Extract the downloaded file, then follow the onscreen instructions. When prompted for your serial number, select Use trial or subscription.
Acrobat XI Standard
If you purchased a subscription to Acrobat XI Standard, a customer care agent needs to help you reinstall. Contact our customer support team.