Mermaid: Set mmdc Command…
mermaid.setMmdcCommand Set the mermaid-cli (mmdc) command or path (blank for the default).
How to run it
Open the command palette (M-x in the Emacs keymap) and search for Mermaid: Set mmdc Command…, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.