See that you asked the same several years ago.
Suggest using a search engine for "Wavepad clean up noise" for numerous tutorials and discussions.
Wavepad has a number of noise reduction tools. Under the TOOLS tab... 
The EFFECTS, LEVELS and Ai tabs might be worth a look as well. Experiment. Share a file of a typical 78 capture here and someone may play around with it.
Upload the file/s to a free server, such as Google Drive or MS OneDrive, right-click the link and Share or Copy. Copy the result and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum. When using Google Drive, click SHARE | SHARE and change "restricted" to "anyone with link can view.**