htaccess remove the parameter from url

Question

I am trying to remove certain url parameters from the urls. Those parameters have no effect on the content being displayed anymore, but google have a bunch of them indexed.

I would like to redirect them to the base url.
Here are the examples.

From www.myexamplesite.com/?start=10
To: www.myexamplesite.com

From www.myexamplesite.com/folder1/?start=10
To: www.myexamplesite.com/folder1

From www.myexamplesite.com/folder2/?start=10
To: www.myexamplesite.com/folder2

Actually I don't need to have any urls with parameters, so I am wondering if there can be a way to catch and redirect all other possible parameters from the urls, and only allow some selected ones that I will specify in htaccess.

Examples:
From www.myexamplesite.com/?param1=10
To: www.myexamplesite.com

From www.myexamplesite.com/?param1=10&param2=20
To: www.myexamplesite.com

From www.myexamplesite.com/folder1/?param1=10
To: www.myexamplesite.com/folder1

From www.myexamplesite.com/folder1/?param1=10&param2=20
To: www.myexamplesite.com/folder1

But for param3 which should be my selected one:

From www.myexamplesite.com/folder1/?param3=10 leave untouched: www.myexamplesite.com/folder1/?param3=10

Update
I actually have already implemented a solution, but my main problem is that it always redirect to the home page and not the appropriate REQUEST_URI...

Here is what I have:

RewriteCond %{QUERY_STRING} .
RewriteCond %{QUERY_STRING} !^item= 
RewriteCond %{REQUEST_URI} !^/manage
RewriteRule .? http://www.myexamplesite.com%{REQUEST_URI}? [R=301,L] 

Answer 1

You can use this rule to strip all query strings except when param3= is found in it.

RewriteEngine On

RewriteCond %{QUERY_STRING} .
RewriteCond %{QUERY_STRING} !(?:^|&)param3= [NC]
RewriteRule ^ %{REQUEST_URI}? [R=301,L,NE]