The word left can mean leaving something behind deliberately or unintentionally (i.e., through forgetfulness).
So, for a sentence like:
I left my umbrella at home.
there is no way to tell if that was intentional or not. However, sometimes context will make it obvious which is case:
I meant to bring my hat, but I left it on the countertop.
Clearly that is an unintentional act, whereas:
I didn't think I'd need a map, so I left the atlas at home.
implies a deliberate decision as opposed to an act of forgetfulness.
M-W has two definitions which seem to account for both of these cases:
a : to cause or allow to be or remain in a specified condition
leave the door open
b : to fail to include or take along
left the notes at home