By launching H-Encore to hack your PS Vita, users will eventually experience a trophy warning whenever they try to open up a game. This guide will show you how to remove this warning by altering H-Encore through VitaShell.
Programs Needed:
VitaShell: GitHub Link

Step 1: Enable Unsafe Homebrews.

• Go to Setting/HENkaku Settings and make sure Enable Unsafe Homebrews is checked.

Step 2: Launch VitaShell.

• Launch VitaShell and go to ux0:user/00/savedata/ and go down to the Folder PCSG90096.
• Press Triangle and press X on Open decrypted.

Step 3: Copy System.dat and remove PCSG90096.

• Go to system.dat, press Triangle and select Copy.
• Press O to go back to ux0:user/00/savedata
• Highlight “..” press Triangle and then Paste.
• Highlight PCSG90096, press Triangle and select Delete.

Step 4: Close VitaShell and Launch H-Encore.

• Exit out of VitaShell and go launch H-Encore.
• The game Bitter Smile will pop up.

Step 5: Close H-Encore/Bitter Smile.

• When you see this screen, close out of the demo, go back to the home screen, and launch VitaShell.

Step 6: In VitaShell Move System.dat Back.

• Back in VitaShell, a new PCSG90096 folder will appear at ux0:user/00/savedata. 
• Highlight system.dat, press Triangle and select Copy.
• Highlight PCSG90096, press Triangle, and then Open decrypted.
• Go to “..” and press Triangle and select Paste.
• Press O to go back to ux0:user/00/savedata, highlight system.dat, press Triangle, and select Delete.
• Now whenever you open a game or app you will no longer get a pop up warning you about not being able to earn trophies.

Note: If you are using games or other apps with saved data from another PSN account you will also get the trophy warning and that is a different issue. Please see my guide here (https://psvitamod.com/saves) to remove that trophy warning.