There is no direct, intended way to delete a deceased Sim's grave or urn from your inventory in The Sims 3 on Xbox 360. The game treats these as permanent keepsakes—part of the family history mechanic. But if a grave is stuck, glitched, or you simply want it gone, here are your options, ranked by safety.
Drag the grave/urn into a Sim's personal inventory (not household). It disappears from world view, stops generating "mourn" interactions, and doesn't affect gameplay. Not a deletion, but functionally equivalent for most players.
Enter Build/Buy mode on a community lot (graveyard, park), place the grave there, then exit. It becomes part of that lot's decoration. You can't retrieve it, but it's out of your inventory.
On Xbox 360, accessing the cheat console is convoluted and unreliable:
testingcheatsenabled true.Reality Check: This method is well-documented on PC but largely non-functional on Xbox 360. The console version strips most debug commands. Even if it works, it can corrupt your save file—lost progress, broken relationships, invisible Sims, or an unloadable neighborhood. Back up your save to a USB drive first (System Settings → Memory → Copy).
If you own the PC version, you cannot transfer the Xbox 360 save to PC, edit it, and move it back. The save formats are incompatible and encrypted differently. This is a dead end.
If the grave's presence is truly game-breaking (rare), your only guaranteed fix is starting a new save file. You lose all progress, skills, relationships, and purchases. Only do this if the save is young or the issue is unbearable.
Best practical advice: store the grave in a Sim's inventory, forget it exists, and keep playing. The game moves on; so should you.