Please find the below article and make changes in the chat.css file.

https://community.pega.com/support/support-articles/disable-attachment-option-client-end-chat-window

Hello Kumar!

This post appears to be a duplicate of your original Question posted a week ago so I will close this as a duplicate.

Please continue the conversation on your original thread.

Thank you!

Marissa | Senior Moderator | Pega Collaboration Center