Hi Jhansi_k ,
You can hide the button in following ways
1. If it is a functional button then you can just go to Admin section and deny permissions for users to use that functionality.
Eg. you don't want users to post in a particular board/ category you can go to Admin settings and deny their permission to post, this will hide the button or make it disabled.
2. You can simply remove that button from the quilt of that page if you have access to the quilt.
3.If you don't have any permission to disable or you don't have access to page quilt to remove standard button component from page, you can also hide it with styling.
To add styling just go to studio>community style>select the required skin> add the required SCSS or css to hide the button.
Hope this helps.
If you find my post useful please Give Kudos or if this is the required solution please mark it as accept as solution
Regards
Tarun kumar