How to access computer remotely?

Hello everyone,
So I have an aunt who runs a business who wants to be able to let the computer run over night at her business and let me access it remotely to do the usual disk cleanup, defrag, virus scans and backups. Currently I have to go on Sundays to do all this and it is just a pain to sit there and wait for the task to complete. I did have some of these automated but some how under the computer illiterate they always get messed up.

Is there a piece of software (preferably free) that will let me access her machine to do all this? It doesn't matter if I need her on the other end to grant me permission to access the machine but I would rather do this from home during the night then do all this on a Sunday. Thanks for any input.

Free TeamViewer Download for Windows

You can also use Windows remote desktop for this but team viewer might be easier to set up.

CopSSH https://www.itefix.no/i2/copssh
Putty
Remote desktop

Works great on all the systems I manage

Teamviewer is probably the best for what you want to do.

LogMeIn and GoSupportNow can do what you want. However, I think LogMeIn is no longer free. GoSupportNow is a paid service.

Your biggest issue is going to be her ISP and her internal network devices. Once those are configured, I'd use RDP if her computer has Pro, or VNC (just my preference) if not.
Remote assistance is also an option, though I'm not that familiar with it since everything I support is Pro. I seem to remember you can create an invitation that lasts for a few days. Maybe create one a week and send it to you ??