diff --git a/src/CollaborationSession/collaborationsession.schema.ts b/src/CollaborationSession/collaborationsession.schema.ts
index 2aa0e5d..b5cf1b8 100644
--- a/src/CollaborationSession/collaborationsession.schema.ts
+++ b/src/CollaborationSession/collaborationsession.schema.ts
@@ -75,6 +75,7 @@ export class CollaborationSessionSchema extends PothosSchema {
           'Retrieve a single collaboration session by its unique identifier.',
         resolve: async (_query, _root, args, ctx, _info) => {
           if (ctx.isSubscription) throw new Error('Not allowed')
+          if (!ctx.http.me) throw new Error('Cannot get your info')
           const scheduleDate = await this.prisma.scheduleDate.findUnique({
             where: {
               id: args.scheduleDateId,
@@ -96,8 +97,19 @@ export class CollaborationSessionSchema extends PothosSchema {
             throw new Error('User not allowed')
           }
           /* ---------- use case 2 : center mentor get collaboration session by schedule date id --------- */
-          if (ctx.http.me?.role !== Role.CENTER_MENTOR)
-            throw new Error('Mentor does not created collaboration session yet')
+          if (
+            ctx.http.me.role !== Role.CENTER_MENTOR &&
+            ctx.http.me.role !== Role.CENTER_OWNER
+          ) {
+            if (!collaborationSession)
+              throw new Error(
+                'Mentor does not created collaboration session yet',
+              )
+            throw new Error('User not allowed')
+          }
+          // check if user is participant
+          if (!scheduleDate.participantIds.includes(ctx.http.me.id))
+            throw new Error('User not allowed')
           // check if order is exist in schedule date
           if (!scheduleDate.orderId) throw new Error('Order not found')
           const order = await this.prisma.order.findUnique({
@@ -131,7 +143,7 @@ export class CollaborationSessionSchema extends PothosSchema {
                 data: {
                   scheduleDateId: scheduleDate.id,
                   // assign chat room
-                  chatRoomId: order.chatRoomId,
+                  chatRoomId: chatRoom.id,
                 },
               })
             // case after start time and before end time, mark as late
diff --git a/src/User/user.schema.ts b/src/User/user.schema.ts
index 1bb1b54..8075867 100644
--- a/src/User/user.schema.ts
+++ b/src/User/user.schema.ts
@@ -8,7 +8,6 @@ import {
 import { Builder, SchemaContext } from '../Graphql/graphql.builder'
 import { PrismaService } from '../Prisma/prisma.service'
 import { clerkClient } from '@clerk/express'
-import { UnauthorizedException } from '@nestjs/common'
 import { MailService } from '../Mail/mail.service'
 import { MessageSchema } from 'src/Message/message.schema'
 import {
@@ -441,8 +440,8 @@ export class UserSchema extends PothosSchema {
           }
           // check context is admin
 
-          if (ctx.http.me?.role !== 'ADMIN') {
-            throw new UnauthorizedException(`Only admin can invite moderator`)
+          if (ctx.http.me?.role !== Role.ADMIN) {
+            throw new Error(`Only admin can invite moderator`)
           }
           return this.prisma.$transaction(async (tx) => {
             let user
@@ -507,6 +506,43 @@ export class UserSchema extends PothosSchema {
           return message
         },
       }),
+      banUser: t.field({
+        type: 'String',
+        args: {
+          userId: t.arg({ type: 'String', required: true }),
+        },
+        resolve: async (_parent, args, ctx) => {
+          if (ctx.isSubscription) {
+            throw new Error('Not allowed')
+          }
+          if (
+            ctx.http.me?.role !== Role.ADMIN &&
+            ctx.http.me?.role !== Role.MODERATOR
+          ) {
+            throw new Error(`Only admin or moderator can ban user`)
+          }
+          if (args.userId === ctx.http.me?.id) {
+            throw new Error(`Cannot ban yourself`)
+          }
+          // get banning user info
+          const banningUser = await this.prisma.user.findUnique({
+            where: { id: args.userId },
+          })
+          if (!banningUser) {
+            throw new Error(`User ${args.userId} not found`)
+          }
+          // if banning user is moderator or admin, throw error
+          if (
+            banningUser.role === Role.MODERATOR ||
+            banningUser.role === Role.ADMIN
+          ) {
+            throw new Error(`Cannot ban moderator or admin`)
+          }
+          // ban user from clerk
+          await clerkClient.users.banUser(args.userId)
+          return 'Banned'
+        },
+      }),
     }))
 
     // Subscription section