When you want to remove a connection from the Connections page in LinkedIn app, then:
Know that when you remove a connection then they will no longer be a 1st-degree connection and will not be seen in your Contacts section.
Open the profile of the member you want to remove in your LinkedIn app.
Now, find the Menu icon in the top right and tap on it.
Then tap on Remove connection.
Use the same method and remove connections from your mobile browser as well.