Note that some built-in Apple apps cannot be deleted. See the following for a list of built-in apps that can be deleted: Delete built-in Apple apps from your iPhone, iPad, or Apple Watch - Apple Support
If the apps you want to delete aren't built-in apps, see below:
If the app is on a Home screen, touch and hold the app, tap Remove app and then tap Delete App (or tap Edit Home Screen in the pop up menu, tap the minus sign, then tap Delete App)
If the app is only in the App Library screen (swipe left past the last Home screen), touch and hold the app there and then tap Delete app.
If neither of those options is available, there may be a restriction set on deleting apps. On an iPhone or iPad, go to Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Deleting Apps.
See: Use parental controls on your child's iPhone and iPad - Apple Support
Also be aware that deleting an app does not cancel any related subscriptions. To do that, see: If you want to cancel a subscription from Apple - Apple Support