You can use Karabiner-Elements with a modification rule imported from here:
The following custom rule that maps Delete to Cmd+Backspace:
~/.config/karabiner/assets/complex_modifications/_finder_custom.json
{
"title": "Finder Custom",
"rules": [
{
"description": "Use Delete as Move to Trash",
"manipulators": [
{
"type": "basic",
"from": {
"key_code": "delete_forward",
"modifiers": {
"optional": ["any"]
}
},
"to": [
{
"key_code": "delete_or_backspace",
"modifiers": ["left_command"]
}
],
"conditions": [
{
"type": "frontmost_application_if",
"bundle_identifiers": [
"^com.apple.finder"
]
}
]
}
]
}
]
}
Then open KE and on the Complex Modifications tab, push +Add Rule and then select your rule from the list.
The downside is that if you rename a file using finder and press the delete (forward-delete) it deletes the text from the cursor to the beginning.
Another downside is that if you click a file on your desktop and try to rename and use the delete key to delete some of the filename text, it deletes the file. While I still have this modification in place I do find I am having to remap my brain to use the backspace key when renaming a file and deleting a portion of the text.
https://github.com/tekezo/Karabiner-Elements/issues/1081