Allow uninstalling banner or PS1 via installer

dotfiles/install/install-linux-global.sh

@@ -94,11 +94,15 @@ fi
 if [[ "$install_ps1" -eq 1 ]]; then
   cp -f "$SRC_PS1" "$DST_PS1"
   chmod 0644 "$DST_PS1"
+else
+  rm -f "$DST_PS1"
 fi
 
 if [[ "$install_banner" -eq 1 ]]; then
   cp -f "$SRC_BANNER" "$DST_BANNER"
   chmod 0644 "$DST_BANNER"
+else
+  rm -f "$DST_BANNER"
 fi
 
 # Ensure /etc/bash.bashrc sources both (idempotent)