Replace "group" with "circle" in the rest of the code

- Remaining mentions already mean "forum"

src/Module/Api/Friendica/Circle/Delete.php

@@ -0,0 +1,78 @@
+<?php
+/**
+ * @copyright Copyright (C) 2010-2023, the Friendica project
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Friendica\Module\Api\Friendica\Circle;
+
+use Friendica\Database\DBA;
+use Friendica\Model\Circle;
+use Friendica\Module\BaseApi;
+use Friendica\Network\HTTPException\BadRequestException;
+
+/**
+ * API endpoint: /api/friendica/group/delete
+ * API endpoint: /api/friendica/circle/delete
+ */
+class Delete extends BaseApi
+{
+	protected function post(array $request = [])
+	{
+		self::checkAllowedScope(self::SCOPE_WRITE);
+		$uid = self::getCurrentUserID();
+
+		$request = $this->getRequest([
+			'gid'  => 0,
+			'name' => ''
+		], $request);
+
+		// params
+
+		// error if no gid specified
+		if ($request['gid'] == 0 || $request['name'] == '') {
+			throw new BadRequestException('gid or name not specified');
+		}
+
+		// error message if specified gid is not in database
+		if (!DBA::exists('group', ['uid' => $uid, 'id' => $request['gid']])) {
+			throw new BadRequestException('gid not available');
+		}
+
+		// error message if specified gid is not in database
+		if (!DBA::exists('group', ['uid' => $uid, 'id' => $request['gid'], 'name' => $request['name']])) {
+			throw new BadRequestException('wrong circle name');
+		}
+
+		// delete circle
+		$gid = Circle::getIdByName($uid, $request['name']);
+		if (empty($request['gid'])) {
+			throw new BadRequestException('other API error');
+		}
+
+		$ret = Circle::remove($gid);
+
+		if ($ret) {
+			// return success
+			$success = ['success' => $ret, 'gid' => $request['gid'], 'name' => $request['name'], 'status' => 'deleted', 'wrong users' => []];
+			$this->response->exit('group_delete', ['$result' => $success], $this->parameters['extension'] ?? null);
+		} else {
+			throw new BadRequestException('other API error');
+		}
+	}
+}