rm is a command-line utility for removing files, directories and symbolic links

adb shell rm /mnt/sdcard/Download/test.apk

Force: remove without confirmation, no error if it doesn't exist

adb shell rm -f /mnt/sdcard/Download/test.apk

Interactive: prompt for confirmation

adb shell rm -i /mnt/sdcard/Download/test.apk

Recursive: remove directory contents

adb shell rm -R /mnt/sdcard/Download

Verbose

adb shell rm -v /mnt/sdcard/Download/test.apk