If you can’t save it and it must be disposed, it would depend on whether or not it has been blessed.
If it has been blessed, it should be buried. If it hasn’t been blessed, it can be thrown away. However, in both cases, it would be advisable to wrap it in cloth or something, so it wouldn’t disturb anyone who happened to find it.
As an aside, I would either bury the crucifix (blessed or not) or save it for some other use.
Here is a related question:
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