Truecaller is a popular app that shows you contact details of unknown numbers calling you. It crowdsources contact details from all its users' address books. So even if you've never used the service, your name and number could be on Truecaller's database, thanks to someone else who's saved your contact details and allowed the app to access them.
Not everyone knows this, but for some fixed-line phones, Truecaller even lists the address of the landline. This doesn't mean much when telemarketers or spammers call from an office address, but ideally you wouldn't want strangers to know your home address just because you called them from your landline. Of course Truecaller sources this data from public data sources. This is because if someone knows your landline number, they can easily find the registered address via any publicly available phonebook (many telcos have this information public) or even by simply searching for your landline number on Google.
For this reason, you should consider removing your number from Truecaller's database. Note that you can't remove your number from the service if you are using the app. You'll have to deactivate your own account to get your number removed. If you were hoping to get just your number removed, while seeing contact details of everyone else who calls, you're out of luck.
Steps to deactivate your Truecaller account
Open the app > tap the people icon in the upper left corner > Settings > About > Deactivate account.
Open the app > tap the gear icon in the top right corner > About Truecaller > Scroll down > Deactivate Truecaller.
Open the app and tap the three dots in the bottom right corner > Settings > Help > Deactivate account.
Once you have deactivated your Truecaller account, you can proceed to removing your number from the service. Here's how.
How to remove your number from Truecaller
Go to the Truecaller unlist page.
Enter your phone number with the correct country code. For example: +911140404040 or +919999999999.
Tick one of the reasons for unlisting, or if you wish, type your reasons for removal in the Other form.
Key in the verification captcha.
Truecaller claims that it removes these numbers up to 24 hours after receiving an unlist request. This doesn't always mean that your number will stay off the service forever. We'd removed our mobile number around a year ago but it started appearing again on the service a few days ago even though we've never used Truecaller. Your best bet is to keep checking with Truecaller users whether they see your contact details. If they don't, you're good to go. If not, you can always ask them to unlist your number.