I am following How to Dual Boot Ubuntu 20.04 LTS and Windows 10 [ 2020 ] | UEFI - GPT Method this tutorial to dual boot my system. I have a 32GB Pendrive and my Pendrive already has 14GB!!! personal data. I am using Rufus and when I click start, it asks that it will destroy the whole Pendrive. Is there any way that I can boot ubuntu in my Pendrive without formating/destroying it!!!
Can I cut and paste all the Pendrive data on my machine?
You should always use a pen drive that has no info on it you need or want.
Copy the info off the pen drive first.
It is not saying destroy as in it will be broken and toss it out, it is saying it will format the drive.
If you create a >3GB FAT32 partition on the pendrive, you can use UNetbootin to install Live USB to the partition without harming anything on another partition: https://unetbootin.github.io/
Unetbootin has a version for Windows, Linux and Mac.
You can also use this method to install multiple OS to multiple partitions on a flash drive using UNetbootin.
Universal USB Installer will also install to a partition on a USB without overwriting other partitions: https://www.pendrivelinux.com/universal-usb-installer-easy-as-1-2-3/
Etcher, dd, Rufus, Disks, mkusb and Win32DiskImager, will overwrite the entire disk.
Partitioning:
Since your flash drive is 32GB it is likely formatted NTFS. This means that you can use Windows 10 Disk Management to shrink the occupied partition and create a new FAT32 partition for UNetbootin or UUI. If the drive is formatted FAT32, you will need Windows third party software or Linux to create a second FAT32 partition.
Cut and Paste
Using UNetbootin or UUI, you do not need to cut and paste any pendrive data. on your machine
