Please refrain from typing in all caps. It makes your post difficult to read.
In the future, please also give details about what exactly you did. Just saying you tried a node doesn’t really give us much information. The specifics tend to matter.
If you’d like to convert 01-APR-2021 to a KNIME date format, you’ll need to first convert the all caps abbreviated month to title case. That is, instead of “APR” it should be “Apr”. This can be done with the capitalize function in the String Manipulation node.
Then you can use the String to Date&Time node to covert the string. Use the date format dd-MMM-yyyy
