I can’t use my Apple Pay on a phone that my little brother gave to me because he has too many accounts on it , how do I get those accounts off or anything of that sort so I can use my Apple Pay pls help

my brother passed down to me this phone

Your brother need to read -> this Apple article: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

Then he has to remove the iPhone from his account, see this Apple article:

Check your Apple ID device list to see where you're signed in

Check your Apple ID device list to find where you're signed in - Apple Support

See also the following Apple articles:

Activation Lock for iPhone, iPad, and iPod touch

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

How to remove Activation Lock

How to remove Activation Lock – Apple Support (UK)

• If you need help removing Activation Lock and have proof of purchase documentation, you can start an Activation Lock support request.

Read this before you use a 2nd hand iPhone.

You can also contact Apple support for help, -> Get Support (apple.com)

You have to show proof of ownership of your product, provide all documentation showing your purchase of the device.

If you do not have additional proof of ownership, contact the reseller. They may be able to provide the original purchase document.

Once Apple receive your proof of ownership, Apple will further review your request and provide an update.

See -> Keep your receipt after you buy an Apple device

Keep your receipt after you buy an Apple device – Apple Support (UK)

he cleared the phone out before he gave it to me ,

He need to check again what posted.