Should I clean up my local machine before installing Docker?
Ultimately, as long as you have the disk space and RAM, you can run both in parallel with very few issues.

The biggest problem you may run into is that the default ports of the applications you run in a container may already be in use.  For example SQL server install runs on port 1433 by default.  If you try to run a SQL server container and do not map a different port on the host machine to 1433 on the container you will run into errors.  This is easy enough do though:

docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=" -p 1431:1433 -d mcr.microsoft.com/mssql/server:2019-CU3-ubuntu-18.04

In the above example, MSSQL server will run on port 1431 and map to port 1433 in the container.  On your local machine you can access either your SQL server on port 1433 or the container SQL server on 1431.