Hello dear.

Change DNS to new IP?
Please run putty or ssh and connect to your server with root then

Use "PEERDNS=no". This option will prevent /etc/resolv.conf from being modified by a DHCP server. So instead of using DHCP-provided DNS, you can specify any arbitrary DNS servers you want to use in /etc/resolv.conf.

The configuration file for your network interface (e.g., eth0) looks like the following.

sudo vi /etc/resolv.conf 

Press enter for continue
for delete u can use of x button on keyboard and then ESC after it use i for edit .conf file and after edit click Esc and then type :wq for save changes

((for more help edit file please click here))

2. Move IP to new Droplet?

-login to digital ocean
Droplets--->click on the name of servers that you want to upgrade on downgrade it--->click on Destroy tab---->then click on Destroy blue button --->

After it you can create a new droplet just should select size ((everything that you want))+ same region*

Have a good day