It is a figure of speech. It can be used to indicate someone has died. But it can also be used to mean many other things depending on context. Think 'kicked the bucket' (another phrase with can be used to denote one's passing).

For example:

Speaker A: Greg kicked the bucket.
Speaker B: Oh! I'm sorry to hear that!

Vs:

Speaker A: Greg accidentally kicked the bucket.
Speaker B: Oh, yes, it was in a rather hazardous location.
Speaker A: The water went everywhere.

Or in the case of 'no more':

Speaker A: Greg is no more...
Speaker B: Oh, I'm sorry to heard that
Speaker A: If you'd let me finish... Greg is no more of a bucket kicker than I am.

It is a figure of speech. It can be used to indicate someone has died. But it can also be used to mean many other things depending on context. Think 'kicked the bucket' (another phrase with can be used to denote one's passing).

For example:

Speaker A: Greg kicked the bucket.
Speaker B: Oh! I'm sorry to hear that!

Vs:

Speaker A: Greg accidentally kicked the bucket.
Speaker B: Oh, yes, it was in a rather hazardous location.
Speaker A: The water went everywhere.

Or in the case of 'no more':

Speaker A: Greg is no more...
Speaker B: Oh, I'm sorry to hear that.
Speaker A: If you'd let me finish... Greg is no more of a bucket kicker than I am.