Are you able to connect the tablet to a computer via USB? That might be your best option for deleting the file you added. Then just restart the tablet after.
If it doesn't work, try a "Factory Reset", it will remove some personal data, but not all. This should remove your added animation as well. This can be done by finding the pinhole on the device (usually on the edge or near where the SD Card and/or SIM cards are installed. Use something small, but not sharp, to depress it.
Should none of the above work, the last option would be a "Hard Reset" which would remove all personal data, apps, etc., so I always suggest using it only as a last resort. Use the following info should you choose to do a "Hard Reset".
NOTE: Doing this will clear the data on your tablet, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the device.
Be sure you back up any data you want to keep, to a computer or cloud account, before doing the reset.
To "Hard Reset" the tablet...
1. Make sure that the tablet is actually powered off.
2. Press the "Power" and the "Volume Up" buttons, together, until you see the start-up logo on the screen.
3. Once you can see the logo, release the buttons and allow the device to enter the "System Recovery Mode".
4. Next use "Volume Down" button to get to the "wipe data/factory reset" option When in recovery mode the "Volume Up" and "Volume Down" buttons are how to can navigate and highlight what option you need.
5. Once you have selected the "wipe data/factory reset", press the "Power" button to select that option.
6. On the following screen, repeatedly press the "Volume Down" button until the "Yes - delete all user data" option is what is selected.
7. Then press the "Power" button to hard reset the tablet.