Is there a way of changing a SharePoint folder name ?

Yes , we can update folder name using update folder metadata integration

in the folder path you can specify the path of the folder which you wanted to rename and the meta data you can pass  as below

a!toJson(
{
"__metadata": { "type": "SP.Data.DocumentsItem" },
/* ri!newFloderName - new foldername which you would like  to provide*/
"Title": ri!newFolderName,
"FileLeafRef": ri!newFolderName
}
)

Thanks for your answer shivanireddys

May I ask what is "FileLeafRef"?

FileLeafRef is the name present at the backend which will not be display to end users, and Name is used as a userDisplay name.

what's the purpose of having that?

with the help of FileLeafRef we can update the properties of folder. if you need any more information you search in the sharepoint documentation. 

Here is the document which has the Internal name of sharepoint fields

How do you target to update a subfolder properties? I've tried your approach and it's always the main folder that's always updating.