I concur this worked for me now, too. I know Batman here advised not to do that (delete stock apps) and his reasoning is legit & sound. But I took the risk anyway &, fortunately, it worked for me and now I have black Google Keep.
I first backed up the app in TiBU, then from within TiBU I wiped the app & cleared its cache then Uninstalled it. Then TWRP, flashed, wiped cache/dalvik, rebooted, profit.
Preferably I would want to be obedient & follow what I'm told not to do, so I'll try to avoid deleting system apps.
Next, now to try & delete Play Store & see if i can finally get it blacked out....lol
1) Uninstalled Updates
2) Ensured that no duplicates or updates folders for the specific app-in-question is present in Data/App folder
3) Opened Titanium Backup & searched for app-in-question
4) Backed-up said app within TiBU (this should be the app version prior to updates installed)
5) Then Wiped Data of said app from within TiBU
6) Then Cleared Cache of said app from within TiBU
7) THEN UNINSTALLED said app within TiBU
8) Rebooted into TWRP
9) Flashed Blacked out app
10) Wiped Cache/Dalvik
13) Detached app from "Market" from within TiBU as I did for, an example, my Play Store just now...
14) Smile & say Thank You in any meaningful way on here.
You can't skip one single step. Especially #14.
15) If your finances allow, donate - (I did).