Every time you add a profile picture to Telegram, the old one is not deleted. People who visit your profile will be able to see all the profile photos you have uploaded since you opened your account. See how you can delete old profile photos in Telegram.
You can always hide your image in Telegram, but the options there are limited. You can either show the profile picture to everyone or just to your contacts. There is no way to completely hide your profile picture in Telegram - your best bet is to remove the profile picture completely.
If you do not want to do this, you can quickly delete old profile pictures. This will ensure that only the most recent photo of your profile is visible to Telegram.
Delete old Telegram profile pictures on iPhone and iPad
Open Telegram on iPhone or iPad and click "Settings", which is located at the bottom line.
Click on the avatar photo at the top.
Now, select the "Edit" button in the upper right corner.
Click your profile picture again.
You will now be able to see all the profile pictures you have uploaded. Keep dragging to the right to see them all. Now go to any image you want to delete and select the trash can icon below the image.
Select "Remove" to delete the image.
You can repeat these steps for all the images you want to remove.
Delete old Telegram profile pictures on Android
The steps for deleting old profile photos are slightly different on Android. Open Telegram on your Android smartphone or tablet and tap the menu icon in the upper left corner.
Select your profile picture.
You can now swipe right on the image to see all your old profile photos. When you find what you want to delete, click the menu icon in the upper right corner.
Select "Delete" from the drop-down menu.
For the second time, press "Delete" and you're done.
You can do the same for all the profile pictures you want to delete.
Source of information: howtogeek.com