Index: bp-core.php
===================================================================
--- bp-core.php	(revision 2316)
+++ bp-core.php	(working copy)
@@ -1609,7 +1609,8 @@
  * @global $bp The global BuddyPress settings variable created in bp_core_setup_globals()
  * @uses check_admin_referer() Checks for a valid security nonce.
  * @uses is_site_admin() Checks to see if the user is a site administrator.
- * @uses wpmu_delete_user() Deletes a user from the system.
+ * @uses wpmu_delete_user() Deletes a user from a MU system.
+ * @uses wp_delete_user() Deletes a user from the system
  */
 function bp_core_delete_account( $user_id = false ) {
 	global $bp;
@@ -1622,13 +1623,17 @@
 		return false;
 
 	/* Site admins should not be allowed to be deleted */
-	if ( is_site_admin( bp_core_get_username( $user_id ) ) )
+	if ( is_site_admin( $user_id ) )
 		return false;
 
-	require_once( ABSPATH . '/wp-admin/includes/mu.php' );
 	require_once( ABSPATH . '/wp-admin/includes/user.php' );
-
-	return wpmu_delete_user( $user_id );
+	
+	if( bp_core_is_multisite() ) {
+		require_once( ABSPATH . '/wp-admin/includes/mu.php' );
+		return wpmu_delete_user( $user_id );
+	} else {
+		return wp_delete_user( $user_id );
+	}
 }
 
 
Index: bp-core/bp-core-wpabstraction.php
===================================================================
--- bp-core/bp-core-wpabstraction.php	(revision 2316)
+++ bp-core/bp-core-wpabstraction.php	(working copy)
@@ -92,10 +92,17 @@
 }
 
 if ( !function_exists( 'is_site_admin' ) ) {
-	function is_site_admin() {
-		if ( current_user_can( 'manage_options' ) )
-			return true;
-
+	function is_site_admin($user_id = false) {
+		if ( function_exists ( 'is_super_admin' ) )
+			return is_super_admin($user_id);
+			
+		if ( !$user_id )
+			return current_user_can( 'manage_options' );
+			
+		$user = new WP_User($user_id);
+		if ( $user->has_cap('manage_options') )
+              return true;	
+			  
 		return false;
 	}
 }