OK, if the exported .csv does not have any headers, can you tell what kind of data is contained in each column, by inspecting the contents? For example, you will hopefully be able to recognize a column that contains passwords, another column that contains usernames, etc. If so, please respond with a numbered list (in which each number corresponds to the column number) of column descriptions. For example, something like the following:
1. (description of contents of first column)
2. (description of contents of second column)
3. (description of contents of third column)
4. etc.
Just to prevent making mess even messier, let’s start over with the original export.
You can certainly delete rows that contain obsolete information, as long as you do it in a way that the entire row is fully removed (i.e., don’t leave behind an “empty” row).
But you will still have to get the columns properly conditioned, which is what I will try to help you with. That is why I need a description of what type of data is in each column of the mSecure export file.
Update:
OK, I researched this a little, and it seems that the mSecure export format is highly irregular, which will make this effort more challenging. Thus, I am modifying my comment accordingly.
First of all, which version of mSecure are you using?
Second, when importing the original (unmodified) .csv file into Bitwarden, what process did you follow? Did you use the browser extension, Desktop app, or Web Vault? Did you select a folder in the “Folder” dropdown menu? Which option did you select for “File Format”?
Bitwarden is supposed to be able to import .csv files that have been exported from mSecure, so we should check that you did this correctly.
If Bitwarden’s mSecure importer is not working as expected, then an alternative option may be to use the “MRC Converter Suite” to convert the mSecure file into some intermediate format that could be imported into Bitwarden.