Hi, hope you are doing good
1. Check webmaster tools - best way to check backlinks and you can find bad links too.
How to check
Step 1: you have to create a webmaster account for your website.
Step 2: few process they will ask to upload the code in the website
Step 3: choose any one method and upload the code in the website
Step 4: login into webmaster tools -> Click your website -> search traffic -> links to your site
Step 5: you can see "who links the most" & "your most linked content" under that you can see more option
Step 6: click and you can see 3 tabs namely download this table, download more sample links & download latest links
Step 7: click the more option under "who links the most" - then download the table
The downloaded format will be and excel. You can analyse and you can able to separate bad links. Create a notepad file with bad links. Inform to Google using Disavow tool. You can upload the notepad file using your webmaster login.
Another tool you can use Ahrefs - top tool but you have to pay and get all the backlinks - free version also available, but they can't provide more.